Added a Show quick connect menu item to show/hide the fast connection box
Merge pull request #368 from muflone/next

Added a Show quick connect menu item to show/hide the fast connection box
Switched to GTK+3.6 threading model, make pthreads compulsory.

Many changes to call GTK/GDK functions only on main thread.
Now libphtreads is compulsory.
Moved GTK calls on main thread.