Draft: Color user-fonts
I have taken Ori Avtalion's patch for color user fonts in !50 (closed), rebased it, fixed up some issues, and added a test.
See !50 (closed) more more details.
I'm not sure if color fonts are supposed supposed to provide CAIRO_SCALED_GLYPH_INFO_SURFACE as well as CAIRO_SCALED_GLYPH_INFO_COLOR_SURFACE. My fixes include generating an A8 image from the color image to be used as the CAIRO_SCALED_GLYPH_INFO_SURFACE.
Edited by Adrian Johnson