Apply Global Shift to Mesh Coordinates

[m-kurz]

Implements a new feature that allows to shift the mesh coordinates using a global shifting vector MeshShift(3).

This feature is particularly useful in cases where the PostDeform functionality is used, which typically acts on a predescribed area of the mesh (i.e. the spherical deformation assuming the origin to be the center of the sphere). In the actual simulation or if other transformation steps are performed it might be beneficial to move that origin to another location after readin from external mesh generators or before writeout, since the simulation (initial/boundary conditions) might expect another location of the coordinate system's origin. The default behavior doesn't change, so it's completely backwards compatible.

One example where this functionality can be useful is a mesh similar to the 2D-2 case defined in: Benchmark Computations of Laminar Flow Around a Cylinder, Schäfer et al. 1996..
The parameter file to generate such a mesh (including shifting) is also added as tutorials/1-06-curved-postdeform/parameter_cylinderinchannel.ini, which also serves as a unit test for the functionality.

The actual shifting is performed in the routines already available for the MeshScale functionality. Scaling and shifting can be both applied independently either just after readin and before writing the mesh to disk. If both are applied in the same stage, scaling is always applied first before shifting the coordinates.

I hope that there is no identical functionality implemented yet that I overlooked...

[kopperp]

Useful feature and clean code, ACK