Add tutorial case

Field mapping following topology change: Dy default additional faces now inherit the internal field values

if they do not have neighbouring faces from which the values may be
interpolated.  Also the old-time flux is set to the current flux values
following correction.  This currently supports only Euler time-schemes.

- space between keyword and bracket in 'for(..)', 'if(..)', 'while(..)'

with the boundary motion before the fluxes are corrected for continuity by
pcorr.