WIP: xpip file input and output

src/core/msrun.cpp

src/core/msrun.h

src/core/project.cpp

src/core/proteinxtp.cpp

src/core/proteinxtp.h

src/input/xpipsaxhandler.cpp

src/input/xpipsaxhandler.h

src/input/xtandemsaxhandler.cpp

src/input/xtpxpipsaxhandler.cpp

src/input/xtpxpipsaxhandler.h

src/output/xpip.cpp