MarkdownEditorView has been renamed and modified to support editing both

Markdown (through CodeMirror) and plain text (through <textarea>). This

edit mode can be set dynamically, allowing a user to choose how whether

a particular field is in rich text mode.
Currently, the default is plain text, which means that when used, all

editors for new objects will show a standard <textarea>. This will

change as I port things over to use the new API.
When placed in an inlineEditor, there will be an "Enable Markdown"

checkbox that the user may check to go in and out of rich text mode.

Tested (along with an upcoming change) in comment dialogs, review request

fields, reviews, replies. Toggled the checkbox and saw smooth transitions

between the entry widgets.
Tested on Chrome and Firefox.