* Add testing feature to Exclusion dialog to allow users to test regexes against an arbitrary string.
* Fixed test suites.
* Improve comments and help dialog box.
* Concatenating regexes into one Pattern might yield better performance under (un)certain conditions.
* Filenames are tested against regexes with no os.sep in them. This may or may not be what we want to do.
And alternative would be to test against the whole (absolute) path of each file, which would filter more agressively.
