Protect lily pads against boats (Adds WORLDGUARD-2601)

This change allows lily pads to be protected against boats. This is important to prevent griefing.

When regions are switched off, lily pads are protected against all boats. When regions are switched on, anyone who has build permissions is able to destroy the lily pad with a boat.

Adds [WORLDGUARD-2601](http://youtrack.sk89q.com/issue/WORLDGUARD-2601)