Allow (non-trailing) "." in qnames?

The DAWG today decided they wanted to be able to use N3 syntax but 
allow "." in qnames (not as trailing). This would rqeuire for 
compatability a change to the n3 grammar, complete elimination of the 
"." for path, and some look ahead in the lexer.

I guess we should try it out (a) in notation3.py, (b) in n3/n3 and (c) 
in the scheduled topic chat.

Tim