Breaking (in creative) can now be undone as well.
Undo/redo now tries to replace the previous blocks, if you have those blocks in your inventory (issue #33).
Fixed undo in survival only undoing blocks that can be broken by hand (issue #29).
Fixed being able to place randomizer bag inside itself (and prevented a black hole from creating) (issue #31).
Randomizer bags can now be placed inside randomizer bags.
Fixed crash when placing with empty randomizer bag (issue #32).
Fixed diagonal wall and slope being 2 blocks thick.