Add Beacon API. Partially adds BUKKIT-2842
Specify that return is a BeaconInventory.
Add BeaconPaidEvent. Partially adds BUKKIT-2842
Change beacon API - remove activation override, add canSeeSky()
Add setNewEffects() to BeaconPaidEvent
Add beacon Properties to InventoryView.
Fix formatting in InventoryView
Add radius & activation override, getDefaultEffects
API Changes: narrow getEffects, use ActivationState enum
Remove setDefaultEffects, add note to header about beacon gui
Specify stricter getHolder() in BeaconInventory