Made a tweak to the noise that both speeds up mapgen and prevents
crashes with Minetest 0.4.11. Also made it so that DM realm structure
spawners automatically remove themselves from the surface world,
preventing griefing.
My visit to OldCoder's Moontest server revealed that CaveRealms was
incompatible with Moontest... but no more! Additionally, griefing in
creative mode was possible because fortress and fountain spawners
appeared in the creative inventory... also fixed. Other measures in
development...
