WME Subtitles

I've ported Mnemonic's subtitle code from WME1 and tweaked it to go with our style and conventions.

This seems to work well enough with both autodetected and 'regular' subtitle files from my demo game (mov_test from my repo wme_testsuite)

I guess that lines with three trailing tokens boils down to "undefined behavior".
In this case I would be particularly wary of differing from the reference implementation - if some developer has a malformed subtitle file that works by blind luck in the original executable, we'd want his blind luck to be portable.