Boundary layer results can be saved in vtk format. Correctly handle inputs fuselage for fuselage and added fuselage type in c++ classes

Now the viscous solver is created after the interface. This allows less user inputs and avoids conflict between parameters. The blSolverInterface class was reworked and documentation was improved. The sections can now have no wake or only one side (for fuselage for example). Bug fix here and there and ajusted tests. Only the onera validation case is up to date.

The data structures of the viscous solver have been reworked to avoid lists of lists of lists... Users now have the possibility to automatically generate sections on wing or to use prescribed section from another mesh. First option requires to identified upper and lower sides and this information is also used by the rbf interpolator.

Removed the requirement of a transfinite surface mesh to generate viscous section. They are now generated by interpolation of the convex hull (wing) using scipy. This works best if we identify the upper and lower sides of the wing. 2 tests are given; NACA0012 airfoil in 2D with RBF interpolation and RAE2822 wing in 3D with rbf as well.  There might be a problem with parallel run of tests. Validation cases are not updated yet. Usage of LFS mesh is prevented on purpose so the 3D validation cases will fail.

Use the function getSolution in utils to get the viscous solution

DART is imported from the submodule if possible or from the blaster install path under blaster/dart. Custom install path can be specified in dartCfg as dart_path.

Avoid forcing installation location

This does not change anything since Minf in the viscous solver is only used to compute the time step

Modified file include accordingly

Results are very close on Mac and ubuntu. Agard test number of iterations is 9 if linear solver is GMRES and 4 if PARDISO. Lift and drag do not change significantly.

The test values are different from mac to ubuntu  which is probably related to version difference (python, numpy, scipy, swig and probably others are different).

 - Revert default value of span. - Removed api test for 3D because it could lead to issues when ctests run in parallel (tests would open the same files at the same time which would cause high latency. - Fixed values of Rae 3D case wrt to previous fix

Plus fixed a bug that would set span to 0