Avoid "using namespace" in header files

source/App/DecoderApp/DecApp.cpp

source/App/DecoderApp/DecApp.h

source/App/DecoderApp/decmain.cpp

source/App/EncoderApp/EncApp.h

source/App/EncoderApp/EncAppCfg.h

source/App/EncoderApp/encmain.cpp

source/App/SEIFilmGrainApp/SEIFilmGrainApp.cpp

source/App/SEIFilmGrainApp/SEIFilmGrainApp.h

source/App/SEIFilmGrainApp/SEIFilmGrainMain.cpp

source/App/SEIRemovalApp/SEIRemovalApp.cpp

source/App/SEIRemovalApp/SEIRemovalApp.h

source/App/SEIRemovalApp/seiremovalmain.cpp

source/App/StreamMergeApp/StreamMergeApp.cpp

source/App/StreamMergeApp/StreamMergeApp.h

source/Lib/EncoderLib/Analyze.h

source/Lib/EncoderLib/CABACWriter.cpp

source/Lib/EncoderLib/EncCfg.h

source/Lib/EncoderLib/EncCu.cpp

source/Lib/EncoderLib/EncLib.cpp

source/Lib/EncoderLib/EncModeCtrl.cpp