Not Entirely Random Item

Added                                                                                                                                                                                                                            
  - Mob Spawner — block that automatically spawns mobs by category; the item in the frame determines the category and Scribble Book entry                                                                                          
  - Display Panel — info display showing the remaining cooldown of an adjacent controller (GiveController, MobSpawner, BlockSpawner, LiquidSpawner, TierRecycler, NERI Bell); shows "Ready!" in green when available               
  - Display Panel integrated with Scribble Book — right-clicking with the book opens the corresponding entry
  - Display Panel integrated with the NERI Bell — shows time until the next ring for bonus loot
  - Display Panel crafting recipe: CCC / FTP / CRC (copper ingots, item frame, clock, black stained glass pane, repeater); recipe advancement triggers on clock in inventory
  - Essence items: Ancient, Decay, End, Nature, Nether, Sculk