Revision 741

(ProjFrame._OnAddToList): Renamed from
        ProjFrame._OnSaveAs. Removed old dead code from previous
        implementation.
(ProjFrame._OnExport): Add support for exporting more than one
        projection to a single file.
(ProjFrame.__FillAvailList): use string formatting (% operator)
        to build strings that are (partly) translated. Fixes RTbug #1818.