GROOVIE: Simplify the movie speed settings and add a GUI option

This removes the "iOS" speed setting, where some movies could get out
of sync. Two movie options are now available, "normal" and "fast" movie
speed, which is the old "tweaked" setting. With the "fast" movie speed,
the movie speed is changed to match that of the iOS version, but only
in movies with sound. Movies without sound (like the supernatural
animations, i.e. the "teeth" icon in-game) are still played at their
regular speed, to avoid music sync issues.
TRANSLATION: Add the new translatable game file in the groovie engine
README: Update documentation on the recently changed t7g movie speed settings
NEWS: Mention the change in the movie speed options of the 7th Guest
MT-32: Sync with the latest changes in munt

This syncs our code with munt commits 3f0db2d and 2c5f314