before merging jacobs code to allow leaving fields as blank in the admin
Merge https://github.com/jacobfan/django-ptree
merged jacobs code to allow leaving fields blank in the admin, and implemented fixes to choices=, esp for nullbooleanfields
added documentation download to ptree admin
various fixes to admin interface, especially session and session participants
On Django Admin Dashboard, make "Sessions" show first, then "Session participants"
fixed the 'text clipping' issue