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 went for consistency (my reasoning: it will be a pleasure to get rid 
of /all/ of them in a single commit later on).

Can strip, of course.