Some comments

Added some documentation and comments to Hazard and the hazard creation
code in LevelControl
Removed HazardControl's listening behaviour

HazardControl no longer listens to PhysicsCollisions, nor does it
extend GhostControl. The hazard objects spawned by LevelControl get
ordinary GhostControls instead, but nothing listens to their collisions.
Adds code that initializes a PhysicsCollisionListener for collisions between the player and hazards.
Changes name of initHazardCollisions to initCollisions in InGameState
FireballControl - a HazardControl test example

Added an instance of the HazardControl interface, FireballControl. When
it hits the player, it reduces his jumpspeed.
Hazards that reduce jumpspeed

Each hazard (blue cube) now has a FireballControl that reduces the
player's jumpspeed each time he hits it. This connects initCollisions
in InGameState, FireballControl, and the HazardControl interface.
Merged hazard-development.
Removed conflicing whitespace.