Removed unused field from 9, removed computer from 4
Removed unnecessary methods from 10, cleaned up artwork
Cleaning up level 11
Removed unnecessary methods in 12, cleaned up art
Removed unused methods, cleaned up level 15
Cleaned up art for level 17
Cleaned up art for 18
Merge pull request #125 from zsweedyk/CleanUpLevels

Clean up levels 9-12, 15, 17, and 18