Small bug-fix release, for Burning Bootloaders Beta team

Bug Fixes

* #612: [BUG]: NullReferenceException thrown on ChipWit Cave (Demo) from fresh game launch
* #626: [BOOMTOWN]: [Classic]: IndexOutOfRangeException when Replaying Boomtown
* #655: [CLASSIC]: Things and Enemies show aberrant spawn and level play behavior and can be on top of one another, invisible
* #658: Bug: Undo does not work after play and back to edit mode
* #663: Bug: NullReferenceException in PuzzleSelectionInitStageState