major updates to db.php, added session.php, run.php uses file_run.php

added db_delete(), db_update(), db_auto_id(), db_replace()
fixed lots of places in db.php where it wasn't passing the mysql link identifier
added redirect() to http.php
run.php now calls file_run() (so you define a function in your file that matches the basename)
   and you can return another basename, and run.php will do that one
session.php uses session cookies (cookies that dissapear when the browser is closed) sessions also expire from the db at a given time