Fixes order of directories specified by -L's so the ones containing newer
glib/gtk will be searched before directories with the older libraries.

and add a utility function that does the moving.

Set the height request of the "You can drop dockable dialogs here"
label to 0, so the toolbox can be properly resized to its minimum
again.

Allow to toggle View->Fullscreen of the empty image window. This
should probably be integrated in session management, but better a fix
that makes it somewhat work than leaving users stuck with a fullscreen
empty window.

The plug-ins use symbols in libm and that's why -lm is necessary, not
because libgimpmath uses it.