Update tests for artificial/* filename rename

lib/flatecut/flatecut_test.go

diff --git a/lib/flatecut/flatecut_test.go b/lib/flatecut/flatecut_test.go
index dc3bc34..b3ad86c 100644
--- a/lib/flatecut/flatecut_test.go
+++ b/lib/flatecut/flatecut_test.go
@@ -25,8 +25,8 @@
 
 func TestCut(tt *testing.T) {
 	testcut.Test(tt, SmallestValidMaxEncodedLen, Cut, newReader, []string{
-		"artificial/deflate-backref-crosses-blocks.deflate",
-		"artificial/deflate-distance-32768.deflate",
+		"artificial-deflate/backref-crosses-blocks.deflate",
+		"artificial-deflate/distance-32768.deflate",
 		"romeo.txt.deflate",
 		"romeo.txt.fixed-huff.deflate",
 	})

test/nia-checksums-of-data.txt

diff --git a/test/nia-checksums-of-data.txt b/test/nia-checksums-of-data.txt
index 200f747..03d5949 100644
--- a/test/nia-checksums-of-data.txt
+++ b/test/nia-checksums-of-data.txt
@@ -6,21 +6,21 @@
 14a5b4b0 test/data/animated-red-blue.000003.nie
 76e40058 test/data/animated-red-blue.apng
 76e40058 test/data/animated-red-blue.gif
-f9a10dac test/data/artificial/gif-background-color.gif
-36e7d9c7 test/data/artificial/gif-empty-palette.gif
-db4c30eb test/data/artificial/gif-frame-out-of-bounds.gif
-fdcc644f test/data/artificial/gif-metadata-empty.gif
-fdcc644f test/data/artificial/gif-metadata-full.gif
-6d03b5f3 test/data/artificial/gif-multiple-graphic-controls.gif
-47c877fd test/data/artificial/gif-multiple-loop-counts.gif
-76c44866 test/data/artificial/gif-no-frames.gif
-6ec818c3 test/data/artificial/gif-pixel-data-none.gif
-5e57adb2 test/data/artificial/gif-pixel-data-not-enough.gif
-3e29f88a test/data/artificial/gif-pixel-data-too-much.gif
-f50d1d50 test/data/artificial/gif-small-frame-interlaced.gif
-beaec397 test/data/artificial/gif-transparent-index.gif
-6ec818c3 test/data/artificial/gif-zero-width-frame.gif
-0564b364 test/data/artificial/png-apng-skip-idat.png
+f9a10dac test/data/artificial-gif/background-color.gif
+36e7d9c7 test/data/artificial-gif/empty-palette.gif
+db4c30eb test/data/artificial-gif/frame-out-of-bounds.gif
+fdcc644f test/data/artificial-gif/metadata-empty.gif
+fdcc644f test/data/artificial-gif/metadata-full.gif
+6d03b5f3 test/data/artificial-gif/multiple-graphic-controls.gif
+47c877fd test/data/artificial-gif/multiple-loop-counts.gif
+76c44866 test/data/artificial-gif/no-frames.gif
+6ec818c3 test/data/artificial-gif/pixel-data-none.gif
+5e57adb2 test/data/artificial-gif/pixel-data-not-enough.gif
+3e29f88a test/data/artificial-gif/pixel-data-too-much.gif
+f50d1d50 test/data/artificial-gif/small-frame-interlaced.gif
+beaec397 test/data/artificial-gif/transparent-index.gif
+6ec818c3 test/data/artificial-gif/zero-width-frame.gif
+0564b364 test/data/artificial-png/apng-skip-idat.png
 076cb375 test/data/bricks-color.bmp
 076cb375 test/data/bricks-color.png
 f36c2e80 test/data/bricks-dither.bmp