Bugfix in the GetSourceRect method.
Big commit ahead of the merge to dev.

- Refactored the GameEngine to contain a list of game actors. Added two actors to test. One of them is a Pawn, the pawn is the primary actor controlled directly by the player input.

- Added wrappers for the std::list. One is a basic list and the other is a special list meant to contain pointers. It contains a method to clear all object and delete their memory.

- Moved Macros to the GameCore project.

- Changed the DirectX project to reflect the changes in GameCore. Now draws as many objects as there are in the GameEngine's list.