Note that spigot doesn't throw events for bamboo yet, so this only
applies to sugar canes and cacti at the moment. Should work if spigot
implements BlockGrowEvent for cacti though.
Fixes WORLDGUARD-4137.
Note that due to deficiencies in the Bukkit API, the event will attempt
to be overprotective and cancel some events that may not actually result
in the player equipping an item. Maintainable PRs welcome. (i.e. would
rather not have to have a list of slot numbers for various inventories
and match them to items :upside_down:)
