Fixed mistake in spoke search - wasn't setting closestSpokeHitDistance for further comparisons.  Isotropic forcing using sqrt(faceArea).  Added 3D analogue of 2D forcing function  - needs experimented with.

Using CGAL-3.4.  Requires to be linked to compiled boost thread library.  In this commit it is hard-coded to -lboost_thread-gcc43-mt-1_37, i.e. boost version 1.37.0, will need to be parameterised.  CGAL does not need to be compiled, as before, and needs the CGAL-3.4/src/files file as before, but the compiler_config.h file, written by cmake, is now included from CGAL/3.4/include/CGAL, where it has been editted to remove the use of GMP.  To use the CMP libraries, add -lgmpxx -lmpfr -lgmp to Make/options - there is little (2%) obvious performance benefit to creating a DT with GMP.  -frounding-math is a required option  - when running in debug assertions failures occur without it when using an exact construction.

Changed mistake in declaring alignmentDirections, now a non-const reference.  Added initial loop outline for cell based looping.

Added isotropic forcing, face area weighted.  Added global aligment to the rotation to alignment method.

important e.g. in atmospheric flows.