Add TODOs.
Indicated expected filename when game starts.
Create warp entity class.
Require warp class.
Spawn warps on map change.
Use correct tilesize value.
Add missing operator.
Change warp appearance.
Clear warp entities between map changes.
Remove unused function and offset code.
Move map changing code out of player class and into world class.
Fix bad variable references.
Abstract adding of main background maps from function.
Abstract player shifting logic from change_map function.
Fix bad entity reference.
Add missing variable data to shift_entities function.
Change order of calls to make code more readable.
Add TODO.
Create warp_to function.
Require warp entity.