Correct zone placement & sizing for underground maps.
Correct placement of subterranean gates.
Somewhat better gate placement, attempt to add rocky tiles to underground zones.
More tweaks.
Correct underground terrains. More improvements for connection placement.
Better gravity-based algorithm.
Throw exception when there are not enough two-way monoliths available.
Fixed gravity algorithm not attracting adjacent zones at all -.-
Merge underground maps with develop. There is a serious issue with rendering rock tiles, which may cause crash.
Merge branch 'RMG' of https://github.com/vcmi/vcmi into RMG
Merge branch 'RMG' of https://github.com/vcmi/vcmi into RMG
Merge branch 'develop' of https://github.com/vcmi/vcmi into RMG

Conflicts:
	Mods/WoG/mod.json
Merge branch 'RMG' of https://github.com/vcmi/vcmi into RMG
Merge branch 'RMG' of https://github.com/vcmi/vcmi into RMG
Integrated and fixed object RMG configs by Kantor.
- Place all standard visitable objects
- Fixed some constructors
Merge branch 'RMG' of https://github.com/vcmi/vcmi into RMG
Generate random Pandora boxes.
Even distribution for surface / underground zones.
- Added faction-specific dwellings
- Fixed generation of terrain-specific objects