catalogue-alias support

[kberry]

The TeX Catalogue has an "alias" concept; for example, the package name xdvipdfmx is an alias for dvipdfmx. This ends up as a catalogue-alias line in texlive.tlpdb.

The Catalogue alias feature is not extensively used, but where it's present, this would (sometimes) provide better results for texdoc than the generic algorithm.

As I recall, there is already a case in texdoc if the argument is an exact package name; the idea would just be to extend that to be if the argument was an alias name as well.

Just a thought ...