Added draft Game implementation.
Made AccelerationEntity a subtype of PositionEntity.
Added basic physics simulator that simulates positions, accelerations and velocities using a naive Euler interpolation.
Changed name from SimpleVelocity to SimpleVelocityEntity.
Filled in overrided functions in EnemyShipImpl.
Changed Enemy class structure and moved implementations to subpackage model.enemy.
Added unit-test project.
Merge branch 'firingFeature' into development
Merge branch 'development' of https://github.com/Jokab/Bullet-Inferno into development
Changed to new physics architecture:
* Removed velocity and acceleration interfaces, they should be handled internally.
* Removed setPosition from PositionEntity, it should be handled internally.
Implemented lists and removed collidables in GameImple