Merge branch 'jvet_m0421_splitsig' into 'master'

source/Lib/CommonLib/ContextModelling.cpp

source/Lib/CommonLib/ContextModelling.h

source/Lib/CommonLib/Contexts.cpp

source/Lib/CommonLib/Contexts.h

source/Lib/CommonLib/TypeDef.h

source/Lib/CommonLib/UnitPartitioner.cpp

source/Lib/CommonLib/UnitPartitioner.h

source/Lib/DecoderLib/CABACReader.cpp

source/Lib/DecoderLib/CABACReader.h

source/Lib/EncoderLib/CABACWriter.cpp

source/Lib/EncoderLib/CABACWriter.h

source/Lib/EncoderLib/EncCu.cpp