wheel: don't autorotate to columns < 0
intro: cancel intro on back press
intro: don't render intro with textured background

looks yacky
current stone: put stone back into wheel when started dragging from the wheel
wheel: don't spin if changing the currently selected stone
wheel: properly fix selecting and changing of current stone without committing and spinning
wheel: rotate wheel to highlighted stone, if just selected
wheel: refactoring to use more generic status enum instead of boolean
wheel: implement flinging of wheel
view: try to make exec thread closer to the desired fps when under load
view: make sure elapsed is never 0.000f, which would break several calculations