-Replaced the rectangular with a more natural circular one.

-Added a new collision method "checkSenseCollision" in <Collision> to
check if the player has walked into a enemy sense area

-Added enemy tile collision
	-Player tile collision and enemy tile collision could be
	 merged into one method, but for now its two separated methods
	 that runs in <Collision> update();
	 
-Moved the "up,down,left,right" booleans and set/get methods to the
superclass <Character>, so that enemies also can use the collision
system, not just <PlayerCharacter>

-Temporary modified move() method in <EnemyCharacter> to illustrate what
could happen when a enemy detects the player by walking into the
senseArea. The senseArea also expands the longer a player is inside it,
to make the enemy more aware of the player the longer he sees him