A quick and dirty Replacement of ckeditor with the Pagedown WYSIWYG Markdown editor to see if it's better.
Prevent id collisions between Pagedown editor panels.

Pagedown requires that the elements it tranforms into its button bar and
preview panel use the ids "wmd-button-bar" and "wmd-preview" with an
optional suffix. To avoid id collisions, all Pagedown editor instances
in our program should use a unique id suffix. The div containing a
Pagedown editor should have class "wysiwyg-panel" and a data-attribute
"data-suffix" giving the id suffix.

For example, the form for entering the content of a new bounty comment
uses a Pagedown editor panel for this input. Its unique id suffix is
"-comment-new-content", so the button bar and preview panel have ids of
"wmd-button-bar-comment-new-content" and
"wmd-preview-comment-new-content".
Avoid compiling the SASS styles twice.

Currently our application compiles most SASS assets twice, by importing
them into custom.css and also including them in application.css. Now
application.css only includes custom.css directly, and custom.css
imports the other stylesheets.
Reorganize the imports in custom.css.sass to be alphabetical to make it easier to check that all files are being imported. Add missing imports discovered by this process.
Replace underscore with dash in the name of the filters stylesheet file to match our naming convention for stylesheets.
Better integrate Pagedown into the rest of the app. Provide a preview window to users when they type Markdown into a Pagedown input field.
The initialization code for Pagedown input fields lets the view customize the title and any classes that are applied to the preview popup.
Apply custom titles and styles to the preview popups for bounty description on the new bounty and edit bounty forms.
Add a comment list partial for the common case of showing a list of comments.
Update the new comment form to use the new hooks for custom title and styles on the preview popup.
Break the new comment form out of the bounty show view and into its own partial, where it belongs.
Now that we have a test-friendly Markdown input editor, reactivate the test for the new comment form.
Update a test for the change in class name of the bounty description input on the new bounty form.