From medieval Dusseldorf to Haywards Heath via a wet afternoon in Merthyr Tydfil, Jonathan Holloway’s jumpcutting timeshifting serial brought Mark Gatiss as Mephistopheles and Julian Rhind-Tutt as the hapless Faust together in a savagely hilarious updating of the Faust myth, underpinned by an inebriated medieval tango band…