Per-gamemode configuration option screen and new run system

[lostkagamine]

This pull request adds a system that allows for gamemodes to have settings configurable within the program by the end user. Press the Hold button, or Tab, on the game mode selection screen to open this menu.

This also merges in #32, the new run system.

[lostkagamine]

it's been two months

[MillaBasset]

I admit I've not been diligent in checking PRs during beta development - it happens when it happens.