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/comsub.right

@@ -1,4 +1,4 @@
-./comsub.tests: line 19: hijkl: command not found
+./comsub.tests: line 21: hijkl: command not found
 argv[1] = <ab>
 argv[2] = <cd>
 argv[1] = <abmn>
@@ -25,6 +25,7 @@ blank ----
 blank ----
 blank ----
 func: v = comsub
+	comsub1.sub
 #esac
 a
 ok 1
@@ -35,10 +36,12 @@ ok 5
 ok 6
 xyz
 ok 7
+	comsub2.sub
 \/tmp\/foo\/bar
 /tmp/foo/bar
 /tmp/foo/bar
 /tmp/foo/bar
+	comsub3.sub
 1
 2
 3
@@ -55,12 +58,14 @@ b
 c
 1
 2
+	comsub4.sub
 d \
 g
 d \
 g
 d \
 g
+	comsub5.sub
 ok 1
 ok 2
 ok 3
@@ -71,6 +76,7 @@ ok 7
 ok 9
 ok 8
 ok 8 
+	comsub6.sub
 Mon Aug 29 20:03:02 EDT 2022
 post foo
 Mon Aug 29 20:03:02 EDT 2022
@@ -82,6 +88,7 @@ Mon Aug 29 20:03:02 EDT 2022
 hey after x
 ./comsub6.sub: line 40: syntax error near unexpected token `)'
 ./comsub6.sub: line 40: `math1)'
+	comsub7.sub
 123
 123
 0