Intro, music and the works

New update, unfortunately much smaller than I anticipated

- added intro to the game, it finally has a proper start

- new audio tracks and proper handling of music between scenes

- AI overhaul, new behaviors and better terrain interaction

- ranged weapons have to be charged by holding the attack button

- attacks can be cancelled with jumping or pressing 'up'

- tables, benches and other background props can be climbed by pressing 'up'

- new climbing animation when climbing a ledge (you guessed it, by pressing'up')

- dozens of bugs covered by another layer of bugs so they're not so visible

- that doesn't mean I haven't squished another 100 bugs along the way