Switched preprocessor defines to be bools instead of just defines
Switched notifications defines to use bools.
Fixed custom mission define to not be a redefine, which can be confusing
Merge branch 'CustomNotifications' into CustomSystems

Conflicts:
	CvGameCoreDLL_Expansion2/CvGameCoreDLL_Expansion2.vs2010.vcxproj
	CvGameCoreDLL_Expansion2/CvGameCoreDLL_Expansion2.vs2010.vcxproj.filters
Merge branch 'CustomMissionDLL' into CustomSystems

Conflicts:
	CvGameCoreDLL_Expansion2/CvGameCoreDLL_Expansion2.vs2010.vcxproj
	CvGameCoreDLL_Expansion2/CvGameCoreDLL_Expansion2.vs2010.vcxproj.filters
	CvGameCoreDLL_Expansion2/CvUnitMission.cpp
	CvGameCoreDLL_Expansion2/ModDefines.h
Merge branch 'CustomSystems' into SiegeMod

Conflicts:
	CvGameCoreDLL_Expansion2/CvUnit.h
Switched SiegeMod over to use preprocessor defines to guard mod code.