Adding underscore-min.js
Simplified level!
Importing underscore.js
Refactoring Level.js to keep track of class-related attributes.
Paying up some technical debt: moved all the image lookup functionality to a map, for cleaner lookup.
Fixed up the map.
More technical debt has been repaid!
Since we have decided to use a simplified map representation, I'm cleaning up the unnecessary assets.
Merge remote-tracking branch 'origin/master'