compiler: implement -stats option for running a _test.v file

* Draft implementation of `v -stats file_test.v` .

* compiler: call stuff in vlib/benchmark/tests/always_imported.v, when doing `v -stats file_test.v`

* Nicer looking output from 'v -stats file_test.v' .

* Tweak colors and layout of -stats file_test.v .

* Fix a hardcoded path in compiler/main.v .

* Show colorized OK/FAIL for the examples in 'v test v' too.

* Add some comments about the purpose of the methods inside vlib/benchmark/tests/always_imported.v .

* when fails are 0, do not colorize their number at all.

vlib/term/can_show_color.v

@@ -7,3 +7,21 @@ pub fn can_show_color_on_stdout() bool {
 pub fn can_show_color_on_stderr() bool {
 	return can_show_color_on_fd(2)
 }
+
+//////////////////////////////////////////////
+
+pub fn ok_message(s string) string {
+	return if can_show_color_on_stdout() {
+		green( s )
+	}else{
+		s
+	}
+}
+
+pub fn fail_message(s string) string {
+	return if can_show_color_on_stdout() {
+		red( s )
+	}else{
+		s
+	}
+}