Allow EAPI 5 in the eclases
Revert "Copy the handling of the gtk-doc in the gnome2.eclass to the mate.eclass. Also added in mate.eclass a DEPEND on both app-util/gtk-doc{-am}."

This reverts commit d94a1a818b3c8cf2bdef23dd5124c0abd7fc7d7a.

Made stupid mistake..
Copy the handling of the gtk-doc in the gnome2.eclass to the mate.eclass.

Also added DEPEND on app-util/gtk-doc{-am} so we do not have to add this to every ebuild.
It is needed anyway so make our lives easier.

Now on to fix the ebuilds.
    Remove DEPEND on app-util/gtk-doc{-am}
    Remove IUSE "doc"
    Update ebuild to use EAPI 5