Improve the quality of text when the scale it is shown at screen is

smaller than the original, seems to work well down to about a scale
of 50%.
* clutter/pango/pangoclutter-fontmap.c:
(pango_clutter_font_map_default_substitute): turn off hinting.
* clutter/pango/pangoclutter-render.c: request linear filtering
instead of nearest neighbour when scaling down.
* tests/test-text.c: replaced test with a a test that renders a sample
grid with various pixel sizes and scales for visual inspection of
text rendering quality.

clutter/pango/pangoclutter-fontmap.c

@@ -196,6 +196,13 @@ pango_clutter_font_map_default_substitute (PangoFcFontMap *fcfontmap,
   if (FcPatternGet (pattern, FC_DPI, 0, &v) == FcResultNoMatch)
     FcPatternAddDouble (pattern, FC_DPI, fontmap->dpi_y);
 #endif
+
+   /* Turn off hinting, since we most of the time are not using the glyphs
+    * from our cache at their nativly rendered resolution
+    */
+   FcPatternDel (pattern, FC_HINTING);
+   FcPatternAddBool (pattern, FC_HINTING, FALSE);
+
   FcDefaultSubstitute (pattern);
 }