enable palette mode for non 4:4:4 color format

source/App/EncoderApp/EncAppCfg.cpp

source/Lib/CommonLib/IntraPrediction.cpp

source/Lib/CommonLib/Slice.h

source/Lib/CommonLib/TypeDef.h

source/Lib/CommonLib/Unit.cpp

source/Lib/CommonLib/Unit.h

source/Lib/DecoderLib/CABACReader.cpp

source/Lib/DecoderLib/DecCu.cpp

source/Lib/DecoderLib/VLCReader.cpp

source/Lib/EncoderLib/CABACWriter.cpp

source/Lib/EncoderLib/EncCu.cpp

source/Lib/EncoderLib/EncModeCtrl.cpp

source/Lib/EncoderLib/IntraSearch.cpp

source/Lib/EncoderLib/IntraSearch.h

source/Lib/EncoderLib/VLCWriter.cpp