views.py:
- BUGFIX: if user submitted form with errors, the second form was not restricted to just the project's sites. The PanelForm needs to know the project
add_site.html:
- make form errors consistent with other forms
view_project_subjects.html:
- added link to add a subject

forms.py, views.py:
- BUGFIX: SubjectForm needs to know the project to restrict the site list to project sites. This is true whether editing an existing subject or adding a new one. Fixed by supplying project_id argument to form when adding a new subject and in the form checking for a Subject instance (and getting the project_id from there) if editing an existing Subject
view_project_panels.py:
- hide panel parameters by default
- added Javascript to show or hide all panel parameters, as well as showing/hiding individual ones