refactored history based merge candidates

source/Lib/CommonLib/CodingStructure.cpp

source/Lib/CommonLib/CodingStructure.h

source/Lib/CommonLib/MotionInfo.h

source/Lib/CommonLib/Slice.cpp

source/Lib/CommonLib/Slice.h

source/Lib/CommonLib/TypeDef.h

source/Lib/CommonLib/UnitTools.cpp

source/Lib/CommonLib/UnitTools.h

source/Lib/DecoderLib/DecCu.cpp

source/Lib/DecoderLib/DecLib.cpp

source/Lib/DecoderLib/DecSlice.cpp

source/Lib/EncoderLib/EncCu.cpp

source/Lib/EncoderLib/EncCu.h

source/Lib/EncoderLib/EncSlice.cpp