Add turbulence model

[FEST3D]

The following turbulence models will be added:

• Wilcox's k-omega 2006 version
• SA one-equation turbulence model
• SST model

[jayten]

References for the models to add:

• Wilcox's k-omega 2006: Wilcox, D. C., "Formulation of the k-omega Turbulence Model Revisited," AIAA Journal, Vol. 46, No. 11, 2008, pp. 2823-2838.
• SST2003: Menter, F. R., Kuntz, M., and Langtry, R., "Ten Years of Industrial Experience with the SST Turbulence Model," Turbulence, Heat and Mass Transfer 4, ed: K. Hanjalic, Y. Nagano, and M. Tummers, Begell House, Inc., 2003, pp. 625 - 632.
• SST: Menter, F. R., "Two-Equation Eddy-Viscosity Turbulence Models for Engineering Applications," AIAA Journal, Vol. 32, No. 8, August 1994, pp. 1598-1605.
• SA: Spalart, P. R. and Allmaras, S. R., "A One-Equation Turbulence Model for Aerodynamic Flows," Recherche Aerospatiale, No. 1, 1994, pp. 5-21.
• WA: Han, X., Rahman, M. M., Agarwal, R. K., "Development and Application of a Wall Distance Free Wray-Agarwal Turbulence Model (WA2018)," AIAA Paper 2018-0593, January 2018.