coding sigma weight
modify lattice api
modify observable.cpp
trying to clarify the big picture here
add .DS_Store to gitignore
add .DS_Store to gitignore
Merge branch 'master' of github.com:kunyuan/Feynman_Simulator
Merge branch 'master' into dev

Conflicts:
	Feynman_Simulator.xcodeproj/xcuserdata/kchen.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist
	src/lattice/lattice.h
	src/lattice/lattice_test.cpp
	src/utility/convention.h
trying to clarify the big picture here