HH damping calibration using damping experimental data

[domniki]

instead of using Darendeli curves from Vs-profile input

[jsh9]

We can readily do this:

• First, we define a Multiple_Damping_Curves object with custom curves (instead of from Darendeli's formulas)
• Then, we use the get_all_HH_x_params() method to do non parametric curve fitting (based on the evolutionary algorithm)

Here is an example: https://github.com/jsh9/PySeismoSoil/blob/455be0fb5c46ab48cbe107b8ec91f852e732d28a/examples/Demo_04_Curves.ipynb (see Section 3: Multiple_Damping_Curves class)