[phpwslistings-dev] Change to ListElements

[Don S. <do...@se...>]

Thanks to Wendall Cada for the proposition, I've dropped the 
"mod_listings_listelements" table and instead will store listing element 
data as a serialized array in a text field in the main mod_listings 
database.

This saves many database interactions for us and hopefully will make 
things a bit leaner and meaner.

This change is in CVS including the upgrade script that will convert 
existing data to the new format and then drop the listelements table and 
it's sequence table.

Don.