Add level limits #18

* Add IsOutsideLevel to check if a unit has moved outside of bounds
* Add GetLevelBounds to get the bounds for the level
Merge remote-tracking branch 'origin/master' into level-limits
Fix unit constructor, checkIfInSideLevel, GraphicsBank get method
Add method to get Level instance from GameObject
Merge remote-tracking branch 'origin/input' into level-limits
Fix case sensitive methodname error
Merge remote-tracking branch 'origin/master' into input
Add warning message for leaving the combat area