switch races for underwater misssions

hopefully the _UNDERWATER string is obscure enough to avoid causing any
compatibility issues.
fix builder error?
Merge branch 'master' of https://github.com/SupSuper/OpenXcom into oXc_kL

Conflicts:
	src/Battlescape/BattlescapeGenerator.cpp
Base::researchHelp() - refactor ... finally

ResearchProject: add consts to params
	- casts, float to double