To end the issues with AA (International) Fonts; the .bfont.tff now is

compiled in (datatoc) and doesn't need installation anymore.

Also reviewed weird path conventions for searching AA fonts;

- U.fontdir is only used as standard search path for fileselecting
- U.fontname stores only full path to AA font if used one
- If a font cannot be found, it always falls back to the compiled in one
- If .B.blend is saved with default font, U.fontname is not set

Also added a button in usermenu "restore default".

When this works as expected, I'll commit changes for installation too.

source/blender/include/datatoc.h

@@ -47,6 +47,9 @@ extern char datatoc_blenderbuttons[];
 extern int datatoc_Bfont_size;
 extern char datatoc_Bfont[];
 
+extern int datatoc_bfont_ttf_size;
+extern char datatoc_bfont_ttf[];
+
 extern int datatoc_cmap_tga_size;
 extern char datatoc_cmap_tga[];