[texdoc] texdoc --apropos

[Karl Berry]

Hi Manuel, 

Jim Hefferon has specified keywords and categorizations now for all CTAN
packages (!).  So I was thinking that texdoc could acquire an --apropros
option, which returns results based on keywords, in addition to the
usual package and doc names.  Probably searching both Jim's list and the
one-line summaries would be best.  Maybe even search descriptions, too.

Jim's data is an enhanced version of the Catalogue, in XML, dumped
nightly.  ftp://tug.ctan.org/ftpmaint/az/texcatalogue.xml
Of course we wouldn't just dump in the whole thing, we'd have to write
something to extract just the keywords in a form that is good for us,
and transform package names (catalogue -> tl) where needed.  
That shouldn't be hard.

I don't think Jim's characterizations, nice as they are, are directly
relevant for texdoc, since texdoc is about displaying documentation, not
browsing directory trees.  You can view it all online at
http://az.ctan.org/ (Jim's test site), though.

Clearly this is future work, nothing to be done quickly or before the
release.   (It came up at the conference.)  I'm sending it now just so
it gets off my list and on to yours :).

Thanks,
k