[LSC] Updated CATEGORY and KEYWORD specs

[William Howard]

I've updated this extension

the new version is here
http://www.ldraw.org/modules.php?op=modload&name=News&file=article&sid=408 

(while Willy's previous version can still be found here
http://www.ldraw.org/modules.php?op=modload&name=News&file=article&sid=340)

I have no idea why PostNuke has corrupted the table of categories (probably
the same reason it ate the main specifications page earlier - it appears to
have removed all embedded styles!)

I have two issues with the extension as it stands

1) Does the LSC really want to be responsible for defining new categories? I
see this as the domain of the PT Admins.  I think the LSC should define the
extension but leave the actual list of categories to the admins (after all
we don't allocate x3DN numbers of pattern suffixes)

2) There was a bit in the !KEYWORDS section about keywords just being space
delimited (as well as comma-space delimited), but then what does "word1,
word2 word3, word 4" mean? Is it three or four terms?  If it's three terms
(as intended), keywords MUST be comma delimited.