Re-enabled sketch rendering for all levels

Updated the levels to:
   1. Specify the proper names for referencing their images for sketch rendering.
   2. Fixed the color coding of various sprites (all black except for Red powerups and Orange death traps)
Updated the vectorizer to a different color threshold to reduce number of vectors per image
Updated the game scene to re-enable sketch rendering for all levels and replace the background with lined paper
Merge pull request #126 from jocelynlih/paul

Re-enabled sketch rendering for all levels