This enables us to store more biome related information in the profiles in the future.
I also changed the default biome profiles directory name back to 'biome' to keep backwards compatibility with Amidst v3.7.
* layer declaration contains logic to calculate the isEnabled and isVisible state
* these states are used by the layer loaders
* fragment loader thread updates these properties and reads the dimension setting at a defined point in the loading cycle
* layer menu uses the same code to calculate the isEnabled state
Stefan Dollase