Added PhysicalObject, refactor some objects to use it. Basis for #4
Refactored Projectile for issue #4
added unit prototype and refactored enemy for issue #4
refactored player related code for issue #4
  * moved initial player settings to config file
  * moved HUD drawing to Conveynace
  * removed projectile list from Player
  * added origin property to Projectile for easy traceback
apparently i cannot use git
Remove some debug lines, rename variables to match style
Merge pull request #5 from nthomson/prototypal_inheritance_refactor

Prototypal inheritance refactor fixes #4