Correct scrolling issues and feedback loop with edit presence (PR #3)

When we amend the textarea we could cause drift of scrollTop due to the code that maintains selection start

In practice if you place the cursor at the end of a text area then scroll to top, then someone else edits, stuff could jump around.

Previous to this change we had a feedback loop where any editor editing would cause other people observing the shared edit to publish state saying they were editing the topic.

This ensures that we only publish state if we actual press the keyboard

also lints files


        const lastKey = this.model.lastKeyPress;

@jjaffeux applied can you approve / merge :heart:

we dont use var anymore, shouod be let or const

k, pushed a fix