Load all levels from data/levels/ after asset loading is complete
Shorten all instances of level to lvl in levelManager
Rename instantiate to lvl_new
Add convenience lvl_new methods
Rename level command to lvl
Log entity position after moving it in edit mode
Refactor ScrollingLevelScreen into CameraScroller, and ripple effects

ScrollingLevelScreen no longer inherits from LevelScreen, and is now its
own isolated class named CameraScroller
Add Camera movement to edit mode (click to move camera)
Move entity buttons after scrolling in edit mode
Add the ability to add entities to a level, and change the background
Create command that saves an edited level, then plays it
Add new background for testing purposes
Load all backgrounds in img/bg/ on startup
Create command to remove entities from a level
Add level created entirely with the level editor!