Untangles dependencies by splitting up `engine.{h,cpp}` into 3 files:
1. `primitive_render`
2. `ticks` -- only contains `GetAnimationFrame` for now.
3. `GetWidth2` renamed to `CalculateSpriteTileCenterX` and moved to `levels/dun_tile.hpp`.
1. Makes START a modifier key.
2. Main modifier actions are now displayed as hints while the modifier is pressed.
3. Mouse simulation now available on all controllers:
SELECT + D-Pad to move mouse
SELECT + Left/Right should button to click
START + | Action
---------- | ------
SELECT | Menu
UP | Menu
DOWN | Map
LEFT | Character info
RIGHT | Inventory
B (Bottom) | Spell book
Y (Left) | Quest log
This makes all actions available on controllers without sticks and ZL/ZR.