[Contract] Localized double-click in teh contract view
Double-clicking on the contract name should open the editor (done
already).
Double-clicking on the contract contractor should open the
contractor(s).
Double-clicking on the contract status should open the status:
e.g., proof for a success, counter-example for a fail, error message for
an error
(from redmine: issue id 2362, created on 2015-06-17, closed on 2015-06-17)