Stores will now refuse to buy your filthy items, probably still covered in blood!

Stores now buy only shiny gems are unique items, but they do so at a much better share.
Price of gems increased tenfolds


git-svn-id: http://svn.net-core.org/repos/t-engine4@2406 51575b47-30f0-44d4-a5cc-537603b46e54