Map updates to 5-1
Code and tile file for different bg
Pre-final 5-1 changes

Probably done.
Merge remote-tracking branch 'origin/master' into leveldesignimprovements
Final changes to 5-1

Let Tim playtest, made a few minor corrections.  Lvl is baked.
Start 9-1 Design Changes

Implement going before origin_x, add backwards easter egg.  Start
redesigning the level for final.
A lot of work on 9-1

Still more to do. :)
More Changes to 9-1
Make whole-map glitches less naive about picking existing tiles (for great glitch justice)
Post-less-naive glitches tuning for 2-1
Added destructible tile to end of level

To reduce chance of being stuck because of the weird "scrolling to end
of level" bug"
Small change to 5-1
Have to stop fiddling with 5-1 :)
9-1 work
Merge pull request #42 from variousauthors/leveldesignimprovements

Leveldesignimprovements