test suite updates: highlight failed test scripts; optionally save failed test output; report number of successful tests; exit based on number of test failures; indent warning messages to make them stand out

tests/mapfile.right

@@ -152,6 +152,7 @@ a
 [28] aaa
 [29] aaa
 declare -a array=([0]="a" [1]="b" [2]="c" [3]=$'\n')
+	mapfile1.sub
 1 2 3 4 5
 foo 0 1
 
@@ -163,6 +164,7 @@ foo 3 4
 
 foo 4 5
 
+	mapfile2.sub
 0 abc
 1 def
 2 ghi