Collision

Implement collision
Collision

Old commit had errors due to git
Observer

Added SoundManager.
Added Observer class
Collision

Added Collision.cs
Scene

Everything within the game scene moves besides the player, so the view
is always fixated on the player and all objects move around.
Entity

Player, Enemy, SceneObstruction and PistolBullet now inherit from
Entity.
Added enum EntityType to Entity.
Tidied up the code
Fixed Warnings

Removed more unnecessary code.
Added additional implementation of input.
Arena

Increased size of Arena texture by 1 pixel on both dimensions.
Implemented boundaries to the arena to deny the player to exit.
Added outer boundaries to the arena texture for when the projectiles are
out of bounds.
Sound

Implemented sound within Enemy.
Improved Collision

Enemies now track the player at the same speed regardless of position.
Collision is between enemies and scenery is now resolved using angles.
Enemy Spawner

EnemySpawner is now fully functioning.
Spawning now occurs on the condition that the player is not within a
certain distance from the spawn point.
The EnemySpawners also contain an amount of enemies they spawn at once
before waiting for the enemies to be reset (get killed).
Removed unnescessary files
Commit all new changes to Master
Merge pull request #4 from ostngag/Rui

Rui