[NPC] Bugs and crawlers

This is a live document. This page is an attempt to iterate through various gameplay concepts and ideas.

Add bugs and crawlers to the list of NPCs

- make them spawn from nests or infected trees trunks? (Any better suggestions?)

- simple walking animation

- squash-able animation (think Mario's Goombas - thanks @RE for suggestion)

- idle animation: rotate randomly on all four axis