Split appearance variables from `Globals` to `EngineGlobals`
Moved `Engine` to the `deps` directory, reworking Makefile
Organized `COMMANDER` and `ENGINE` targets on the Makefile
No need for the `Game` subdirectory anymore
Cleaned up `commander` a bit
Made `Window` have borders by default, according to `EngineGlobals`
Cleaned up minor thingy on `StateManager` and `main.cpp`