:startDoc, setPrintContext): hand through to the font map

:startDoc, setPrintContext): hand through to the font map

* xpdf/GPOutputDev.cc (GPOutputDev::startDoc, setPrintContext):
hand through to the font map
(getStreamContents): adapted from glib
(getFontFaceEmbedded): new, uses experimental
gpdf_gnome_print_add_font
(getFontFace): use getFontFaceEmbedded for fonts with embedded
font files

* xpdf/GPOutputDev.h: update declarations,
(GPOFontMap::startDoc, setPrintContext): implemented inline

* xpdf/gpdf-view.cc (gpdf_view_set_pdf_doc): call startDoc

* xpdf/gpdf-gnome-font.h, xpdf/gpdf-gnome-font.c: new files;
hackish implementation of gnome_print_add_font

* xpdf/Makefile.am (gnome_pdf_viewer_SOURCES): add
gpdf-gnome-font.[hc]