Implement collision control

[louisayd]

• Create a table data structure in order to lookup whether or not given tiles are solid / passable
• Flag tiles as solid when parsing the csv files
• Keep track of players and AI's current tile location
• Perform a solidity check when moving into a new tile (return True if passable, false otherwise)
• Generate a CollisionEvent when the new tile is found to be impassable
• Handle collision between enemies and players properly