Various minor changes to tutorial scripts. In particular, ensuring that
they all change to the containing directory so that batches of tutorials
can be run easily from the root of the installation.
The initial set of cases in the test directory are aimed at testing the
reactingEulerFoam populationBalance functionality.
Patch contributed by Institute of Fluid Dynamics, Helmholtz-Zentrum
Dresden - Rossendorf (HZDR) and VTT Technical Research Centre of Finland Ltd.
Integrated with the "tutorials" functionality by CFD Direct Ltd.