Refactor api + updated tests with mode updater and added scalers

API only works for 2D cases

+ Refactor adjoint and api's

The api features 3 components: The solver, the geometry and the initial mesh. The api is tested in a aerodynamic shape case where the NACA0012 is constrained at 0deg AoA with cl=0.40 and the objective function to minimize is the drag wrt the max camber and the max camber position. The test case ends with a final shape close to the NACA4412 (camber = 35% & max camber pos = 41%)

Fixed API, dart interface and prevented segfault if the number of sections is not imposed correctly.

Contains 2D and 3D developements as well as the api.