multiple choice dialogs
Merge branch 'master64' of github.com:elliotwoods/ofxCvGui2 into master64

Conflicts:
	Example_ElementTree/._build
	ofxCvGuiLib/ofxCvGuiLib.vcxproj
	ofxCvGuiLib/ofxCvGuiLib.vcxproj.filters
	src/ofxCvGui/Panels/World.cpp
	src/ofxCvGui/Widgets/MultipleChoice.h