Adding plugins for Moodle as requested flts

Add the following plugings to Moodle:

http://moodle.org/plugins/view.php?plugin=mod_choicegroup

http://moodle.org/plugins/view.php?plugin=mod_dataform

http://moodle.org/plugins/view.php?plugin=mod_pcast

http://moodle.org/plugins/view.php?plugin=local_dsubscription

http://moodle.org/plugins/view.php?plugin=block_accessibility

http://moodle.org/plugins/view.php?plugin=block_quickcourselist

http://moodle.org/plugins/view.php?plugin=block_course_contacts
Adding new versions of modules and blocks. Also some bugfixes with kent changes to core moodle
Adding latest turnitin tool mod and applying our changes to it. Also a number of access.php changes to modules and blocks to stop moodle errors
Update context_user
Update to context_course
Add myaddinstance cap
Add new langs to course contacts
Define..
Merge kent changes