Nobody has them anymore, and they are deprecated in GTK+ 3.x. This
also fixes all conflicting mnemonics except those I missed, but we can
fix them now.
Change GimpFileDialog's file-procs properties to enum
GimpFileProcedureGroup and get them via the newly added API. Set
properties common to all dialogs in the parent class.
The code refactoring allows better readability which will allow in turn
to add more complex specific features making good use of the save/export
split concept.
Michael Natterer