Configurable Biome GUI

[marcbal]

Is your feature request related to a problem? Please describe.
When creating new challenge, we have the ability to give players the ability to set the island’s biome. Players can set the biome using the command /is biome <biome> (when they have the permission), but they may not being aware of the availability of the biome when they use the biome GUI.

Describe the solution you'd like
Have the ability to configure the list of biomes available in the biome GUI. For instance, a config file (or section in existing file) would look like this:

biome-gui:
  ocean: # use the key of the biome, like the one given by Biome.getKet().getKey()
    displayItem: tropical_fish
    description: "The ocean biome is the basic..."
  forest:
    displayItem: spruce_sapling
    description: "The forest biome will allow..."

Describe alternatives you've considered
Manually add new biomes to the GUI in the code of the plugin.

Additional context
Would help solving issues #39 and partially #40

[minoneer]

Thanks for your input! I have updated the biome system - please take a look if that works for you :)