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)

@somaen would it make /any/ sense to turn this into a helper class and put uit under Common?
Aka: is there anything else that uses MicroDVD .SUB files?