Get rid of head panel in editor

The head panel takes a lot of space, that can better be used for displaying the segments.

In addition customers who already disabled the head panel for themselves want a customizable area in the right column.

So it makes sense to move the customizable area of the head panel into a certain area of the right panel (see linked extra issue) and to put the functionality that is available in the header in the top menu. How this works shows the attached image.

The logout button and the leave task button must be able to hide via Zf_configuration for those users, that do use translate5 editor stand alone. This has to be documented in confluence, where the editor-only mode is documented.