Remove use of 'using namespace std'

...ce/App/BitstreamExtractorApp/BitstreamExtractorAppCfg.cpp

source/App/DecoderApp/DecApp.cpp

source/App/DecoderApp/DecAppCfg.cpp

source/App/DecoderApp/decmain.cpp

source/App/EncoderApp/EncApp.cpp

source/App/EncoderApp/EncAppCfg.cpp

source/App/SEIFilmGrainApp/SEIFilmGrainApp.cpp

source/App/SEIFilmGrainApp/SEIFilmGrainAppCfg.cpp

source/App/SEIRemovalApp/SEIRemovalApp.cpp

source/App/SEIRemovalApp/SEIRemovalAppCfg.cpp

source/App/StreamMergeApp/StreamMergeApp.cpp

source/App/StreamMergeApp/StreamMergeAppCfg.cpp

source/Lib/CommonLib/BitStream.cpp

source/Lib/CommonLib/IbcHashMap.cpp

source/Lib/DecoderLib/AnnexBread.cpp

source/Lib/DecoderLib/NALread.cpp

source/Lib/EncoderLib/EncCu.cpp

source/Lib/EncoderLib/EncGOP.cpp

source/Lib/EncoderLib/EncLib.cpp

source/Lib/EncoderLib/EncModeCtrl.cpp