New things for the new version

Added a setup_plugins.php file
... it checks all the folders in plugins/ and adds all the plugins (each file in thos folders is a plugin) into the plugins.xml file. For each plugin it asks you for the events at which it starts and for all the events at which the plugin is stopped.

This events should be chosen with care.

Hopefully before the next release I won't have to change this file anymore ... it seems to work. :)