Set a minimum length for wrapping text

Fixes #199.
diff --git a/help.go b/help.go
index 1b0c2c6..9167847 100644
--- a/help.go
+++ b/help.go
@@ -107,6 +107,10 @@
 func wrapText(s string, l int, prefix string) string {
 	var ret string
 
+	if l < 10 {
+		l = 10
+	}
+
 	// Basic text wrapping of s at spaces to fit in l
 	lines := strings.Split(s, "\n")