[poppler] Metadata changes

[Jonathan Blandford]

Hi,

I just added metadata support to the glib-bindings for poppler.  This is
pretty straightforward, though I had to add a new enum to Catalog.h to
get the PageLayout field.  It's not completely perfect yet.  The pdf
version is always 1.5 right now, and I ran out of steam when
implementing ViewerPreferences.  However, they should be straightforward
to add/fix.

I updated test-poppler-glib appropriately.

Thanks,
-Jonathan