Fix Bug 575138: It is possible to zoom below zoom level 0
Fix Bug 575138: It is possible to zoom below zoom level 0

potyl/champlain,StanciuMarius/Libchamplain-map-wrapping,GNOME/perl-Gtk2-Champlain,Distrotech/libchamplain,PabloCastellano/libchamplain,StanciuMarius/Libchamplain-map-wrapping,potyl/champlain,StanciuMarius/Libchamplain-map-wrapping,StanciuMarius/Libchamplain-map-wrapping,potyl/champlain,potyl/champlain,GNOME/perl-Champlain,PabloCastellano/libchamplain,StanciuMarius/Libchamplain-map-wrapping,Distrotech/libchamplain,Distrotech/libchamplain,PabloCastellano/libchamplain,PabloCastellano/libchamplain,PabloCastellano/libchamplain,GNOME/perl-Gtk2-Champlain,GNOME/libchamplain,GNOME/libchamplain,GNOME/perl-Champlain,Distrotech/libchamplain,Distrotech/libchamplain