Strip filename of junk; add regexes. Issue #79:

Remove the random junk off the end of the filename before parsing it
using regexes, fixes cases where the show name is (partially) numeric
such as 'the.100.208...'

Also add another couple of regexes - we should now have pretty good
coverage of the different input filename formats, and can be pretty
confident in changing the regexes as the test seems to cover a decent
variety of input filenames.