Use enumeration for BDPCM mode

source/Lib/CommonLib/ContextModelling.cpp

source/Lib/CommonLib/ContextModelling.h

source/Lib/CommonLib/DeblockingFilter.cpp

source/Lib/CommonLib/IntraPrediction.cpp

source/Lib/CommonLib/IntraPrediction.h

source/Lib/CommonLib/Quant.cpp

source/Lib/CommonLib/QuantRDOQ.cpp

source/Lib/CommonLib/QuantRDOQ.h

source/Lib/CommonLib/TrQuant.cpp

source/Lib/CommonLib/TypeDef.h

source/Lib/CommonLib/Unit.cpp

source/Lib/CommonLib/Unit.h

source/Lib/CommonLib/UnitTools.cpp

source/Lib/CommonLib/UnitTools.h

source/Lib/CommonLib/dtrace_blockstatistics.cpp

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