Change x_fileselect_add_preview argument to GedaFileChooser
Update from master for NL translations
Conditionally set the default font directive
Expand configuration utility functions in i_var.c
libgedauio: Add new Image Chooser Dialog object
Minor code cleaning, update Doxygen comments
Add defines for configuration group and filter key(s)
Replace x_dialog_select_file with GedaImageChooser Dialog
Add Preview Widget to GedaImageChooser Dialogs