libview: Allow printing to all formats supported by backend

Set output format of EvPrintOperationExport according to the format
requested by user or by capabilities of used backend if there
is only 1 choice.

https://bugzilla.gnome.org/show_bug.cgi?id=724044
libview: Show correct warning when printing

Show that requested format is not supported by printer
if it is not supported.

https://bugzilla.gnome.org/show_bug.cgi?id=724044
Updated Hungarian translation
Fix a crash during the build with introspection enabled

Using GI_SCANNER_DEBUG=save-temps, the temporal files remained.
It has been suggested that calling gtk_style_context_add_provider_for_screen()
should, inside a g_once_init(), be in the class's _init() (not class_init()) hook.

https://bugzilla.gnome.org/show_bug.cgi?id=726812
ev-window: Fix enable caret navigation question message

https://bugzilla.gnome.org/show_bug.cgi?id=727062
thumbnails: Remove extra call to ev_document_get_page_size
doap: update URLs