More changes to various files for new flags
Also adds to_string and from_string methods to the bitset template
Merge branch 'bitset_flags' of https://github.com/scp-fs2open/fs2open.github.com into bitset_flags

Conflicts:
	code/ai/aicode.cpp
	code/fred2/shipflagsdlg.cpp
	code/globalincs/pstypes.h
	code/hud/hud.cpp
	code/hud/hudtarget.cpp
	code/menuui/techmenu.cpp
	code/network/multimsgs.cpp
	code/pilotfile/csg.cpp
	code/ship/ship.h
	code/ship/shipfx.cpp
	code/ship/shiphit.cpp