This is a cleanup of the instruments table to trim the lengths down
to more reasonable numbers. Do note that we also drop both the "list"
and "underlyingid" columns here, they are not needed since MDA builds 
the same information (and in a better way) in the "listmappings" and 
"underlyings" tables but end users should first check that they don't 
have code that use the old columns before dropping them!!!
