Add alien containment management to game

Accessible by right clicking alien containment in base view.  Invoked
automatically if alienContainmentLimitEnforced is enabled and
containment limit is exceeded after a mission.
Add files to commit
Rename files
Centre ok button
More renaming and centering
Ensure available and used space does not include aliens under research
Merge branch 'master' into containmentManagement

Conflicts:
	bin/data/Language/en-US.yml
	src/CMakeLists.txt
Add additional strings to en-GB too
Alter containment management screen colors
Merge branch 'containmentManagement' of https://github.com/cfailde/OpenXcom

Conflicts:
	bin/data/Language/en-GB.yml
	bin/data/Language/en-US.yml