Merge pull request #3615 from minrk/ansilinux

Fix regular expression for ANSI escapes, which wouldn't catch `\x1b[01;`, only `\x1b[0;` or `\x1b[1;`.

Closes #3614.
expand ANSI color support

adds support for 256 colors

does not yet add support for themed 16-color mapping ([01;38;5;[0-15])

closes #3617