Made sure all resources are no longer marked as purgeable so they stay
in memory (not that we were running out), also cleaned up some other
code issues.
I've added a new level select scene after picking your set, and I've
updated the engine to store the result of each puzzle separately. The
level select is paged (can't fit all 50 on one screen), so needed to add
a new "previous button" graphic.
Added confirmation prompts, so I can prompt before quitting, and for a
new menu option to clear your scores if you want to reset your progress.
Progress is still not persisted when you exit, as I haven't figured out
how to do that yet.
I've also rearranged the title screen a bit.
* Added a proper event loop
* Added minimal menu bars
* Added about menu
* GameWindow initializes a GameEngine (even if you can't play it yet)
* Updated variable naming conventions
* Added base "Hello MacLO" app
* Added first attempt at porting game engine from [ArduLO](https://github.com/jonthysell/ArduLO)
* Added README.md and LICENSE.md
