Video skipping is done with the escape key and is enabled by default,
but can be disabled with the new "skip support" game option to keep
the original game behavior where video skipping isn't possible
This adds volume control to the game by setting the mixer sound type on the
various audio streams to values other than the default "plain".
This uses the following sound types:
Ambient (music, environment sounds): music
AI voice: speech
Effects, interface, footsteps, movie audio: SFX
This could be further improved by specifying sound types for individual sounds,
f.e. SFX for environment sounds, or music for the "effects" in the appartment
which are short musical cues. The movie audio is of course pre-mixed music,
speech and SFX.