Remove cross-hairs from PredictionGraphPane forms
Allow unfiltered HTML in a few Sequence fields

Fixes some user-reported bugs (superscripts being hidden in authoring display)
Fix ridiculous CSS reset which treats <sup> as regular text

If <sup> isn't displayed as a superscript, the reset breaks semantic HTML and gives users (PARTICULARLY users used to writing for STEM) the idea that the site is somehow broken because their superscript tags don't work.
Fixing permissions bug with creating panes

[#57606942] See code comments: when a join model has no instances to join, return true for edit_permitted? instead of fruitlessly trying to find its parent.

https://www.pivotaltracker.com/story/show/57606942
Merge branch 'refs/heads/master' into production