Replace "go get" advice with "go install"

Fixes #62
diff --git a/cmd/ractool/data.go b/cmd/ractool/data.go
index 5e1a5f3..ec00c72 100644
--- a/cmd/ractool/data.go
+++ b/cmd/ractool/data.go
@@ -124,7 +124,7 @@
 
 Like any other implemented-in-Go program, to install the ractool program:
 
-    go get github.com/google/wuffs/cmd/ractool
+    go install github.com/google/wuffs/cmd/ractool
 
 Extended Example:
 
diff --git a/cmd/ractool/main.go b/cmd/ractool/main.go
index f91ad53..6aaca3b 100644
--- a/cmd/ractool/main.go
+++ b/cmd/ractool/main.go
@@ -125,7 +125,7 @@
 
 Like any other implemented-in-Go program, to install the ractool program:
 
-    go get github.com/google/wuffs/cmd/ractool
+    go install github.com/google/wuffs/cmd/ractool
 
 Extended Example:
 
diff --git a/doc/benchmarks.md b/doc/benchmarks.md
index 97ac47a..00b8e48 100644
--- a/doc/benchmarks.md
+++ b/doc/benchmarks.md
@@ -38,7 +38,7 @@
 [benchstat](https://godoc.org/golang.org/x/perf/cmd/benchstat) tool. For
 example, that tool can calculate confidence intervals based on multiple
 benchmark runs, or calculate p-values when comparing numbers before and after a
-code change. To install it, first install Go, then run `go get
+code change. To install it, first install Go, then run `go install
 golang.org/x/perf/cmd/benchstat`.
 
 
diff --git a/doc/getting-started.md b/doc/getting-started.md
index 4fac53c..b1e6c78 100644
--- a/doc/getting-started.md
+++ b/doc/getting-started.md
@@ -22,15 +22,25 @@
 well as C libraries (and their .h files) like libjpeg and libpng, as some tests
 compare that Wuffs produces exactly the same output as these other libraries.
 
-Running `go get -v github.com/google/wuffs/cmd/...` will download and install
-the Wuffs tools. Change `get` to `install` to re-install those programs without
-downloading, e.g. after you've modified their source code, or after a manually
-issued `git pull`. The Wuffs tools that you'll most often use are `wuffsfmt`
+Run `git clone https://github.com/google/wuffs.git` to get the latest Wuffs
+code, `cd` into its directory and run `go install -v ./cmd/wuffs*` to install
+the Wuffs tools. The Wuffs tools that you'll most often use are `wuffsfmt`
 (analogous to `clang-format`, `gofmt` or `rustfmt`) and `wuffs` (roughly
 analogous to `make`, `go` or `cargo`).
 
-You should now be able to run `wuffs test`. If all goes well, you should see
-some output containing the word "PASS" multiple times.
+You should now be able to run `wuffs test`. If you only have the `gcc` C
+compiler installed, but not `clang`, then you can run `wuffs
+test -ccompilers=gcc` instead. If all goes well, you should see some output
+containing the word "PASS" multiple times.
+
+Remember to re-run `go install etc` whenever you've modified the Wuffs *tools'*
+source code (i.e. `*.go` files) or after a manually issued `git pull`. If
+you're only modifying the Wuffs *standard library's* source code (i.e.
+`*.wuffs` files), re-running `go install etc` is unnecessary.
+
+If you're modifying just one particular codec in the standard library, such as
+the `std/png/*.wuffs` files, then you can exclude unrelated tests by running
+`wuffs test std/png`.
 
 
 ## Poking Around
diff --git a/doc/spec/rac-spec.md b/doc/spec/rac-spec.md
index 94a457d..ac06ae7 100644
--- a/doc/spec/rac-spec.md
+++ b/doc/spec/rac-spec.md
@@ -661,7 +661,7 @@
   - [RAC](https://godoc.org/github.com/google/wuffs/lib/rac)
   - [RAC + Zlib](https://godoc.org/github.com/google/wuffs/lib/raczlib)
 
-Command line tool, installable via `go get
+Command line tool, installable via `go install
 github.com/google/wuffs/cmd/ractool`:
 
   - [ractool](https://godoc.org/github.com/google/wuffs/cmd/ractool)
diff --git a/hello-wuffs-c/run.sh b/hello-wuffs-c/run.sh
index ac3f9a6..aa0ff8b 100755
--- a/hello-wuffs-c/run.sh
+++ b/hello-wuffs-c/run.sh
@@ -18,7 +18,7 @@
 CC=${CC:-gcc}
 
 # You may need to run
-#   go get github.com/google/wuffs/cmd/wuffs-c
+#   go install github.com/google/wuffs/cmd/wuffs-c
 # beforehand, to install the wuffs-c compiler.
 wuffs-c gen -package_name demo < parse.wuffs > parse.c
 
diff --git a/script/bench-c-deflate-fragmentation.c b/script/bench-c-deflate-fragmentation.c
index 73734d3..2adb601 100644
--- a/script/bench-c-deflate-fragmentation.c
+++ b/script/bench-c-deflate-fragmentation.c
@@ -396,7 +396,7 @@
       "compatible with the\n"
       "# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install "
       "it, first\n"
-      "# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n");
+      "# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n");
 
   for (int i = 0; i < 5; i++) {
     msg = decode(true, true);
diff --git a/script/bench-go-deflate/main.go b/script/bench-go-deflate/main.go
index 8603f03..afe89e3 100644
--- a/script/bench-go-deflate/main.go
+++ b/script/bench-go-deflate/main.go
@@ -81,7 +81,7 @@
 	fmt.Printf("#\n")
 	fmt.Printf("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n")
 	fmt.Printf("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n")
-	fmt.Printf("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n")
+	fmt.Printf("# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n")
 
 	for i := -1; i < reps; i++ {
 		for _, tc := range testCases {
diff --git a/script/bench-go-gif/main.go b/script/bench-go-gif/main.go
index 590ea2d..4dd74b2 100644
--- a/script/bench-go-gif/main.go
+++ b/script/bench-go-gif/main.go
@@ -106,7 +106,7 @@
 	fmt.Printf("#\n")
 	fmt.Printf("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n")
 	fmt.Printf("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n")
-	fmt.Printf("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n")
+	fmt.Printf("# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n")
 
 	for i := -1; i < reps; i++ {
 		for _, tc := range testCases {
diff --git a/script/bench-go-png/main.go b/script/bench-go-png/main.go
index f462572..e6bd31c 100644
--- a/script/bench-go-png/main.go
+++ b/script/bench-go-png/main.go
@@ -90,7 +90,7 @@
 	fmt.Printf("#\n")
 	fmt.Printf("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n")
 	fmt.Printf("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n")
-	fmt.Printf("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n")
+	fmt.Printf("# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n")
 
 	for i := -1; i < reps; i++ {
 		for _, tc := range testCases {
diff --git a/script/bench-rust-deflate/src/main.rs b/script/bench-rust-deflate/src/main.rs
index f83a02d..84b2008 100644
--- a/script/bench-rust-deflate/src/main.rs
+++ b/script/bench-rust-deflate/src/main.rs
@@ -47,7 +47,7 @@
     print!("#\n");
     print!("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n");
     print!("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n");
-    print!("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n");
+    print!("# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n");
 
     let mut dst = vec![0u8; 64 * 1024 * 1024];
 
diff --git a/script/bench-rust-gif/src/main.rs b/script/bench-rust-gif/src/main.rs
index e7ca737..a99db8c 100644
--- a/script/bench-rust-gif/src/main.rs
+++ b/script/bench-rust-gif/src/main.rs
@@ -52,7 +52,7 @@
     print!("#\n");
     print!("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n");
     print!("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n");
-    print!("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n");
+    print!("# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n");
 
     let mut dst = vec![0u8; 64 * 1024 * 1024];
 
diff --git a/script/bench-rust-png/src/main.rs b/script/bench-rust-png/src/main.rs
index 166b7f9..ca7be26 100644
--- a/script/bench-rust-png/src/main.rs
+++ b/script/bench-rust-png/src/main.rs
@@ -45,7 +45,7 @@
     print!("#\n");
     print!("# The output format, including the \"Benchmark\" prefixes, is compatible with the\n");
     print!("# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install it, first\n");
-    print!("# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n");
+    print!("# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n");
 
     let mut dst0 = vec![0u8; 64 * 1024 * 1024];
     let mut dst1 = vec![0u8; 64 * 1024 * 1024];
diff --git a/test/c/testlib/testlib.c b/test/c/testlib/testlib.c
index 3ebd2d8..9b099cc 100644
--- a/test/c/testlib/testlib.c
+++ b/test/c/testlib/testlib.c
@@ -422,7 +422,7 @@
         "compatible with the\n"
         "# https://godoc.org/golang.org/x/perf/cmd/benchstat tool. To install "
         "it, first\n"
-        "# install Go, then run \"go get golang.org/x/perf/cmd/benchstat\".\n");
+        "# install Go, then run \"go install golang.org/x/perf/cmd/benchstat\".\n");
   }
 
   for (int i = 0; i < reps; i++) {