Preliminary implementation
More updates
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
More updates in the TNE2 structure
Updated solution & variable classes for TNE2 solver
Updated solution & variable classes for TNE2 solver
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
Still modifying TNE variable class.
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
Updated the Roe solver for TNE2.
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
Updates to the TNE2 solver in the numerics class.
Updated the structure of the TNE2 solver to be consistent with the rest of the SU2_CFD source code.
Revamped variable class for TNE2 model.
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
Major update to variable class, solver class and EulerWall, SymmetryPlane, and FarField B.C.s
Updates to numerics class in the TNE2 solver.  Debugging implementation.
Merge branch 'master' of https://github.com/su2code/SU2 into feature_TNE2
Bug fixes in the TNE2 CVariable initialization