[Fontconfig] Firefox & Typeface Selection

[Jorge Fábregas]

Thanks a lot Raimund for the wonderful explanation.  Now I understand :)
 I see your point that how the typefaces are expanded on the "family"
list after substitution, and their resulting order, is really what
matters generally.

The FC_DEBUG=4... was also interesting (I could see how the list was
being created).

Thanks! Much appreciated.

All the best,
Jorge