pangomm: New API in pangomm 1.10

# New API in pangomm 1.10

Member Pango::CairoFontMap::create_context ()

Member Pango::CairoFontMap::get_resolution () const

Member Pango::CairoFontMap::set_resolution (double dpi)

Member Pango::Context::get_font_options () const

Member Pango::Context::get_resolution () const

Member Pango::Context::set_cairo_font_options (const Cairo::FontOptions& options)

Member Pango::Context::set_resolution (double dpi)

Member Pango::Font::get_font_map () const