concepts updated

I have now processed my actions from April 11th see:
http://lists.w3.org/Archives/Public/w3c-rdfcore-wg/2003Apr/0207.html

I attach the current version of

http://www.w3.org/2001/sw/RDFCore/TR/WD-rdf-concepts-20030117/Overview.html

for the record.

Note: the ToC is incorrect, I will fix this after the change to the datatype
numbering.

I will now work on:

- getting it up to date with the other issue resolutions
- renumbering the datatypes section as agreed.

Jeremy