Remove exosip stuff, correct warnings in sipcall

configure.ac

src/Makefile.am

src/managerimpl.cpp

src/managerimpl.h

src/sipcall.cpp

src/sipcall.h

src/sipmanager.cpp

src/sipmanager.h

src/sipvoiplink.cpp

src/sipvoiplink.h

src/voiplink.h