Change Ace references to self in closures
Cleanup

* Remove extra property for meta box and only show theme selection field on Gistpens
Not nix, shell
Whitespace cleanup
Switch Ace theme selection from CMB to bespoke
Register Gistfile post_type
Split editor class into post + gistpen
Massive edit page overhaul

* Replace editor with rendered editor
* Remove excess DOM manipulation
* Remove extra AJAX calls
* Save new Gistpens to Gistfile, attached via postmeta
* Clean up editor look
Add repeatable editor

* Split JS into two files
  * Over Gistpen editor obj
  * Indiv Gistfile editor obj
* Properly render initial Gistfile editor
* Wire up button to add and delete Gistfile editors
* Correctly attach all Gistfile to Gistpen
Merge branch 'feature/has-many-files' into develop

* feature/has-many-files:
  Add repeatable editor
  Massive edit page overhaul
  Split editor class into post + gistpen
  Register Gistfile post_type
  Switch Ace theme selection from CMB to bespoke
  Whitespace cleanup
  Not nix, shell
  Cleanup
  Change Ace references to self in closures