Delaunay triangulation and piecewise-affine Registriation

[BSeppke]

To finish my point-pairs based registration algorithm contribution, I'd like to add this code to the master. The idea behind the piecewise-affine registration is that the point sets are first delaunay triangulated. Then, the contents of each triangle in the source image is transformed using an affine transformation to the target triangle. Since the delaunay triangulation uses LEMON, both - the delaunay triangulation as well as the piecewise-affine registration need (and check for!) the WITH_LEMON condition. A test is also included by means of an extension to the registration/test.cxx test.

Best wishes, Benjamin