Allow Test::Builder::Tester to use regex matching

TBT has had an undocumented version of this ability for ten years.
This commit improves the interface slightly, documents it, and
fixes the color highlighting to work.

This is important because even with plain old strings we ran into
broken color highlighting! This was a result of magically changing
standard failing messages into regexes internally to cope with the
change in output format.

Of course, we wouldn't need *any* of this if we used a more
modern library (i.e. one that wasn't deprecated) and fragile to
change, but there you go.
slightly better documentation for Test::Builder::Tester
fixup example in documentation in Test::Builder::Tester
quiet some warnings by passing "" as type in testsuite
Merge pull request #414 from 2shortplanks/master

Test::Builder::Tester coloring fix / document and improve undocumented regex matching feature