Open Terrain Generator (OTG)

Note: When updating OTG 1.12.2 be sure to delete OTG-Core.jar or it will not be updated.

- Added GravityFactor setting to the worldconfig (this requires a Forge client with OTG). Forge only atm, can be used to change the gravity of a world/dimension.
- Some fixes for dims when using other mods that add dims.
- Smoothing fix for terrain (will cause minor seams in your world when entering newly generated terrain, looks much nicer though! See: https://cdn.discordapp.com/attachments/285816707040280586/415940913848647690/output_8hRRQB.gif).
- Savetodisk infinite loop fixed (one instance, there may still be more).
- DIM folders being recreated on server restart bug fixed.
- Fixed a bug for Lost Cities dimension.
- Added a method for Spigot plugin developers (requested on the git).
- Added TERRAIN_GENERATOR dimension tag when sending other mods (like RC) dimension info via Forge IMC when an OTG dimension is created/destroyed.
- Frozensurfacehelper stackoverflow bug fixed (thanks BrainStone).
- BO3 CustomStructures now try to avoid vanilla structures as much as they can.
- Added /otg biomes command for Forge for debugging biome registry problems.