Unit moves with speed defined in its UnitDesc
Balance: Peon speed 5 -> 4, Grunt speed 7 -> 6
BuildeOrder: Update() Being build state factorization
Quick and dirty collision implementation
Fixe: BoundingBox should always has a width/height greater or equal than 1
MoveOrder: collision check *less* uggly implementation
Fixe: Unit doesn't stay stuck on building when popping after training/building
Render every unit bounding box in grey (selected unit is still in green)