Features in Educational
+ Adding key binding 'F' to verify StarBlockList integrity (checks for large jumps in magnitudes between neighbouring StarBlocks in an SBL)
+ Adding key binding 'G' to print the structure of the LRU Cache
+ Adding timing code to output time elapsed in various segments of the most recent draw() loop, bound to key 'B'
+ Fixing quite a few serious bugs
+ Adding more error / warning messages