* glom/glom.glade:
	* glom/utility_widgets/dialog_image_progress.h:
	* glom/utility_widgets/dialog_image_progress.cc:
	* glom/utility_widgets/Makefile.am: Added a dialog which loads an
	image and shows progress of the operation.

	* glom/utility_widgets/imageglom.h:
	* glom/utility_widgets/imageglom.cc: Use this dialog when the user
	selects an image to load, to indicate progress for large images.