Add keyboard events

[pafnutovalex]

mousedown, mouseenter events are good, but not enough. When the user go to the editable div by pressing tab on keyboard, the editable panel doesn't show up.

You can see this even on Demo page by pressing tab few times unless it will be focused on Title.

This is important when some fields are editable without etch formatting (like title) and following others are with etch formatting.

My suggestion is use focusin, focusout.