Add config option to whitelist dimensions for meteorite gen

Depends on API change (https://github.com/AppliedEnergistics/Applied-Energistics-2-API#37), build will fail until then.

Adds a new entry to the worldGen section of the config to specify a list of ids to whitelist for worldgen with a default of { 1 }. (you can specify 1 and -1, but meteorite gen doesn't work in these dimensions)