Recursive Schema Support

Adds support for recursive (a.k.a. "circular" or "self-referential") schemas.  Also, make definition order not matter.

This requires a non-backwards compatible change to the Editor API, so this pull request will be the first v0.7 release.

TODO:
*  [x] Recursive schema support
    *  [x] In oneOf (not first oneOf choice)
    *  [x] In array items
    *  [x] In pattern properties
*  [x] Ignore definition declaration order when resolving references
*  [ ] Helpful warnings when infinite recursion is detected
*  [x] Way to mark object properties as not added by default
    *  [x] Recursive schema support within these non-default properties 
*  [x] Overhaul of object properties modal
*  [x] Fix broken dynamic header support (including tab labels)
*  [x] Crease recursive.html example
*  [x] Update documentation
*  [ ] Test!!!



Fixes #71 
Fixes #142 
Fixes #115 
Fixes #128 
Fixes #153 
Fixes #181 
Fixes #110