oUpdate class definitions to use slots= rather than representation().

   oBumped requirement for DBI up to version 0.3.1 or greater.

   oAdjusted TSconnect() to use a string or a connection in place of a
   driver, and renamed argument drv to q to reflect this change.

   oSome tweaks to TSfinddb() for new versions of database packages
   using new version of DBI.


git-svn-id: svn://svn.r-forge.r-project.org/svnroot/tsdbi@511 edb9625f-4e0d-4859-8d74-9fd3b1da38cb