Tabulated aerodynamic coefficients

[aleixpinardell]

Support added to provide aerodynamic coefficients as a function of altitude.

A unit test has been added. The result of the test on my laptop was:
6/127 Test #6: test_TabulatedAerodynamicCoefficients .................... Passed 2.06 sec
when using a tolerance of 1E-12, but failed for 1E-18. The tolerance is currently set to 1E-12, and thus all the 127 tests passed.

The test uses a list of altitudes and drag coefficients. The other aerodynamic coefficients were always set to 0 and thus they have not been tested.

[DominicDirkx]

Hi Aleix,

Thanks for writing the unit test! I made some modifications and will push it to the master shortly.

A few small things:

• I changed the testing approach a bit: the test now uses the altitude of the output to evaluate the original interpolator, to check whether the coefficients are properly evaluated at each time step. This prevents issues with teh altitude not necessarily being continuously increasing, and focuses more on the correct usage of the aerodynamics during the propagation.

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http://tudat.tudelft.nl/projects/tudat/wiki/N_Commandments
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