better connection handling

src/gui/official/PhoneLineManagerImpl.cpp

src/gui/official/PhoneLineManagerImpl.hpp

src/gui/official/RequesterImpl.cpp

src/gui/official/RequesterImpl.hpp

src/gui/official/SFLPhoneApp.cpp

src/gui/official/SFLPhoneWindow.cpp

src/gui/official/SFLPhoneWindow.hpp

src/gui/official/Session.cpp

src/gui/official/Session.hpp

src/gui/official/SessionIO.hpp

src/gui/official/TCPSessionIO.cpp

src/gui/official/TCPSessionIO.hpp

src/gui/official/TCPSessionIOCreator.cpp