Changed variable names

To improva readability throughout classes
Modifies the fixture definitions

Now all the Box2d bodies got the same fixture definitions
Implemented a choosable debug renderer
Added a contact listener for collision detection

Also added dispose method for Box2D variables.
Created a Bullet class.
Refactored some code into a method
Created a weapon to the player Box2D body

Created a body as a weapon and jointed it together with the player. The
weapon will always be attached to the player at the same place.
Implemented player rotation
Modified bullet class to handle angle of direction
Created shoot method
Tested gitignore
Merge branch 'playerabilities' into develop