* glom/utility_widgets/dialog_image_save_progress.[h|cc]:
* ui/operator/dialog_image_save_progress.glade:
Added a progress dialog to do image saving, though it does not yet do
async saving so the dialog is never shown.
* Makefile.am:
* Makefile_glom.am:
* po/POTFILES.in: Mention the new files.
  * glom/utility_widgets/imageglom.[h|cc]: Add the new context menu items,
  using a temporary file for the Open and Open With features.
  Open With uses AppChooserDialog to offer a choice to the user.
  Bug #630057