Added new game launch/return effect.
Fix vertical and horizontal GuiBox images being flipped.
Fixed ScrollableContainer clipping.
Changed game select effect to interpolate more interestingly.
Fixed really sneaky texture deallocation bug.
Textures allocated with no path (e.g. the transition image which uses
copyScreen()) weren't being deinitialized with the renderer.  Which meant
something else could take the old texture ID, and when the no-path texture
got destroyed, it would take a texture along with it.
Remove debug text.
Finally add a license (MIT).