Rudimentary audio system implemented

Started work on a very bare-bones audio system. Currently loads audio
files as per the audio config file, all in .wav format, and then puts
them into the audio_reg registry. Each sound consists of a sample, a
category and an id for that category. Allows us to call certain sounds
randomly or by specific cat/id pairing.

Should make things easier.

Aside from that, I've also removed some greened-out code that no longer
served a purpose.