Geographicraft

Added configs for beach biomes, using biome identifier names rather than IDs. A biome can be assigned a beach from another mod.

Biomes o Plenty biomes now have gravel beaches when appropriate.

Added a config to set external biomes by biome identifier name rather than by ID. Identifiers will override IDs, and setting by ID# should be considered deprecated.

Suggestions on default beaches warmly welcomed. I don't remotely have the time to test 300 or so biomes.

Also: I am very seriously considering configs for subbiomes. If you want them, squeak.