Rough draft of WEPIF for WorldEdit-Forge. Mainly for FE compatibility, but other mods can implement this if they so want.

This commit removes ForgeUtil, with its 2 methods relocated. To set a permissions provider, get the instance of ForgeWorldEdit, and call setPermissionsProvider with an instance of a class implementing ForgePermissionsProvider.
Merge pull request #309 from luacs1998/master

Add temporary permissions API for the Forge mod.