Implement UFSCC parallel emptiness-check

CMakeLists.txt

src/CommonSOG.h

src/LDDGraph.cpp

src/MCMultiCore/ModelCheckerCPPThread.cpp

src/MCMultiCore/ModelCheckerCPPThread.h

src/ModelCheckBaseMT.h

src/algorithm/CNDFS.cpp

src/algorithm/UFSCC.cpp

src/algorithm/UFSCC.h

src/main.cpp

src/misc/SafeMap.cpp

src/misc/SafeMap.h