trigger a new revision from the UI

Hi all,

Currently revision creation is based on inactivity after last change. If there are some minutes in between changes then a new revision is created.

This helps already a lot.

Sometimes I wish to have a defined version, like it is done on a commit in git or gdoc revisions.

So my wish is about to get at least the revision created. This may need a new UI element "save current revision"

What do you think about this?