Trees

- Collidable trees
- Objects place themselves in their containers
- Trees get their 'stump' image
- Multiple object types can be created. (ugly if-else loop. We need to find something better!)
- x & y locations of objects passed through constructor. 
- Added tree stumps and rocks on map. More tiles have collision. 
- Added a player and rabbit spawnpoint on the map.

NOTE: Je moet rebuilden voordat de nieuwe map gebruikt word! 

@PimV @basvandenheuvel Willen jullie nog controleren voor ik dit merge? Aangezien ik ook wat aan de collidableTile creation en class gezeten heb.