moved camera as child of player, PlayerMovement controls rotation, enemies face player instead of camera now.
added up/down for mouse movement.
moved vertical rotation to player, fixed movement so that we're only moving on x/z plane.
Fixed bullets to fire where crosshairs point now.
changed player movement to fixed update.  set player rigidbody to kinematic and gave rigidbodies to barrel, wall, cactus.
Merge branch 'fps'