* plug-ins/common/poppler.c: merged in all the changes in my
	current gimp-poppler tree that don't need c++ or cause regressions.
	Insignificant code cleanups.

	* plug-ins/common/poppler.c (load_dialog): display title of pdf
	at the top of the dialog, and show the page labels in the page
	selector.  The loop for the page labels might be profitably moved
	into another thread, but I haven't actually timed how long it takes
	to be sure.