Added audio

Audio additions include 2 nick cage lines. One to theme the game to 'put
the bunny back in the box' the other a sound trigger by ak47 pickup to
describe the ak.
Made weapons able to fire many missiles

Weapons can now have a limit specified that allows several active
missiles at once up to that limit. Each missile is rendered and updated
well.

Todo: Of course, the rendering of  the missiles need proper z order
rendering as does all other entities.

Todo: The player needs feedback on when they are firing a weapon too
quickly, so they can avoid overheating the weapon easily.