Show State of Visual in Task-List

The current task List for a Project does not show any icon for the Visual. This is impractical for PMs working with visuals or for maintainers solving service requests.

Solution: add column "Visual" in the task list of a project showing an icon of the state of the visual review.  A green checkmark stands for a fully functional visual review (both screens), a yellowish exclamationmark stands for a incomplete visual without Live Editing and a red "x" stands for no visual. A

Mouseover over the icon gives further details: If the Visual was connected to the source or targets, the number of html-pages of the visual (not pages of the PDF) , a note when the text-reflow has failed and a note if the visual originated of an aligned XML

Should be implemented together with TRANSLATE-1994