random duck jump
The first few screens now only require 30mb, instead of 143mb.
Merge branch 'master' into fix_characters
Fix the character select screen and overworld.

These scenes no longer import all their resources when imported. That
happens now on enter.
Starting a level works
Merge branch 'master' into fix_characters
Levels work, but the flyin screen is still broken
Correct drawing of floorspace sprites.
Merge pull request #1827 from DaNiwa/draw_sprites

Correct drawing of floorspace sprites.
Add ability to mark gamestates as paused. Fix #1825

Instead of having to pass around the level, we add a new method `stack`
that marks the current gamestate as paused. This will have no effect on
non-level gamestates. Nodes also don't have to have a reference to the
level to make this work.
Fix the flyin.
The overworld now works.
Merge pull request #1829 from hawkthorne/pause_levels

Add ability to mark gamestates as paused. Fix #1825
Fix global flags reference
Merge pull request #1818 from hawkthorne/fix_characters

Improve memory footprint
ducks start jumping different times
reduce player's health
Require is bad
Fix variable typo
Add support for OS X 10.9