Rename JVET_C0024_ZERO_OUT_TH and clean up related functions

CMakeLists.txt

doc/software-manual.tex

source/Lib/CommonLib/CommonDef.h

source/Lib/CommonLib/ContextModelling.cpp

source/Lib/CommonLib/ContextModelling.h

source/Lib/CommonLib/DepQuant.cpp

source/Lib/CommonLib/Quant.cpp

source/Lib/CommonLib/QuantRDOQ.cpp

source/Lib/CommonLib/Rom.cpp

source/Lib/CommonLib/TrQuant.cpp

source/Lib/CommonLib/Unit.cpp

source/Lib/DecoderLib/CABACReader.cpp

source/Lib/EncoderLib/CABACWriter.cpp