Moved core files from libs directory to src

src/core/music/tmeasure.cpp

src/core/music/tmeasure.h

src/core/music/tmelody.cpp

src/core/music/tmelody.h

src/core/music/tmeter.cpp

src/core/music/tmeter.h

src/core/music/tnamestylefilter.cpp

src/core/music/tnamestylefilter.h

src/core/music/tnote.cpp

src/core/music/tnote.h

src/core/music/tnotestruct.cpp

src/core/music/tnotestruct.h

src/core/music/trhythm.cpp

src/core/music/trhythm.h

src/core/music/trtmgroup.cpp

src/core/music/trtmgroup.h

src/core/music/ttechnical.cpp

src/core/music/ttechnical.h

src/core/music/ttune.cpp

src/core/music/ttune.h