Implement Factions support - protect claimed chunks

Factions is optional, and does not need to be present on the server.
Drop towny from this - towny can't be optional afaics.
Don't create clay except underwater in clay-natural regions.

This prevents ocean islands etc. from creating clay blocks above water,
and from non-clay natural regions from creating any type of clay
underwater, which doesn't fit well in Minecraft landscapes.
Handle ores.

- move just as fast as stone
- very low chance of degrading into stone
Slow down progressively under deeper water.

This preserves the deeper oceans while still having a good effect on shallow
water - it'll create a bit of a bulge near the coastline that looks more natural and
won't erode coastlines as much as the versions before.