* glib/ListBase.cs : add a nested class to support filename encoded
string element marshaling.
* gtk/Gtk.metadata : mark the filenames and folders as filename
encoded.
* gtk/FileChooserDialog.custom : use new ListBase.FilenameString type
for list element type of filenames and folders.
* gtk/FileChooserWidget.custom : use new ListBase.FilenameString type
for list element type of filenames and folders.
[Fixes#72701]
svn path=/trunk/gtk-sharp/; revision=45334
