Update Pistol, Thing, Bullet.
Add PROPOSAL, README, GUIDE txts.
Fix Actor death bug in Game.
Fix compiler errors.
Move weapon from Actor to Player; only the player needs a weapon\!
Add mouse input to Game.
Make Actor/Thing addition/removal infrastructure.
Add recover function to weapon to be called when mouse is up.
Add Pistol logic.
Fix focus issue in Main.
Add takeDamage function; updates health, dies if appropriate.
Add Bullet logic.
Fix pistol/bullet logic.
Add color to BasicEnemy.
Make screen static
Implement bullet movement, make size reasonable.
Merge branch 'feature-weapon' into develop