Destructive Chaser added

Making this was a good refresher.  My code is starting to be better organised now that I know what I'll need and when. There's still plenty of room for improvement, but I'm steadily getting better. I intend to regularly make a new prototype, as a sort of Panda3D coding kata.

Raw keyboard events is by far my favorite Panda3D feature. Other engines probably have something similar.  It's just so comfortable to be able to adapt to most (all?) keyboard layouts without having to make a whole 'configure your input keys' menu.

Something obvious that I missed when I first started with Panda3D, is to have multiple CollisionHandlers. The Destructive Chaser prototype uses an EventCollisionHandler for things like the walls getting crushed and the player getting caught and a CollisionHandlerPusher to make the blocks and edges of the screen impassable for the player.