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.
Example of an explicit coupling between OpenFOAM and an external application using the externalCoupled boundary conditions. The case is based on the buoyantCavity tutorial case, whereby on each iteration the 'hot' and 'cold' patch temperatures are incremented by 1K.