[#1641] Save window size and position in sflphonedrc

...-client-gnome/src/dbus/configurationmanager-introspec.xml

sflphone-client-gnome/src/dbus/dbus.c

sflphone-client-gnome/src/dbus/dbus.h

sflphone-client-gnome/src/mainwindow.c

sflphone-common/src/dbus/configurationmanager-introspec.xml

sflphone-common/src/dbus/configurationmanager.cpp

sflphone-common/src/dbus/configurationmanager.h

sflphone-common/src/managerimpl.cpp

sflphone-common/src/user_cfg.h