Concrete5: heartbeat on content block while in edit mode...

[fmaruna]

We are having to suffer through a strict 15 minute session logout now.
Its not uncommon for someone to have a page open in edit mode, have a content block open, and just be typing away for more than 15 mins. When they goto hit save, they are now logged out.

This isn't a problem in composer as we auto-save drafts.
We don't really need all of that here, and we dont want a new version every 5 minutes, but it would be cool if the content block had some little neato thing where it just polled with JS if keystrokes were happening and sent a little arbitrary heartbeat to the server...

[mlocati]

I already used a script that does that for another (non concrete5) project.
It should be easy to implement it. Tomorrow I'll submit a PR

[mlocati]

See #7681