TODOs.txt

Entity::pos should be private & EntityMap should be a friend of Entity
Entity's position should be set only while it is being inserted into an EntityMap,
	only have a getPos() and pos should not be changeable except through the move function
		this would obviate the need for certain checks & also make things safer...

Improve EntityMap routines so that we don't always need to create set<Entity *> &collidingEntities
	Question - how do signal a collision? Would exceptions ever be a good/acceptable idea for this?
	           What other ideal alternatives exist? 

Use/implement C++11 move semantics:
	...

port to SDL
use SDL's flip
use SDL rectangle intersection function