No issue
- removes more usage of function prototype extensions in favor of Ember functions
- replaces some event calls with the direct function name
- adds comments to functions replaced with the event name
closes#4368, fixes#1240 (spellcheck), fixes#4974 & fixes#4983 (caret positioning bugs)
- Drop CodeMirror in favour of a plain text area
- Use rangyinputs to handle selections cross-browser
- Create an API for interacting with the textarea
- Replace marker manager with a much simpler image manager
- Reimplement shortcuts, including some bug fixes