Added /is setspawn command to set the islands spawn point
* You must be the owner of the island to use it
Added /is warp and /is togglewarp
* /is warp <player> warps to the specified players island spawn
* /is togglewarp toggles allowing and disallowing warping to your island
Cleaned up the permissions, added missing permission nodes
Fixed sethome and setspawn expecting wrong number of arguments