add variable_del to hook_uninstall, instead of using DELETE FROM {variable}, which is error prone to getting too much

#208301 - fix query when DISTINCT is used (which also adds a GROUP BY clause) - this is really a hack, and won't work with subqueries, a better regex fix is still needed

fix bug in FROM replacement when subselects are used; remove unused function str_replace_first; use fields as first case for finding the sort column (I'm not sure if the logic here is best)

#136449 - add support for table views