Remove trailing whitespace
Update spell checker ui so that it's less glitchy.
* Change CSS so that the suggestion menu is on top of the loading menu
* Ensure loading menu is always closed after suggestion menu creation
* Prevent duplicate suggestion menus from being created
* Add a 500ms delay to the suggestion hover so that the menu isn't as easy to open inadvertently while scrolling, etc
* Use the data attribute for the add-to-dictionary functionality for better reliability (eg we don't want to send the text of the whole dom node across as the word to add to dictionary).
* Don't attempt to remove menus that no longer exist