Audio Queue System

This week I implemented an audio queueing system so that audio clips don't get cut off when a new level starts. Currently we just add a new clip at the start of the level, but eventually we'll be able to do things like add clips under specific conditions and fade in & out of audio sources. This will be really useful when we have several audio sources at once (Radio narration, Kid narration, music, SFX), and meanwhile it helps make transitions seamless.