Interpolation Options for Trajectory Resampling

[niclaswue]

This PR adresses issue #440.

Changes made:

• added interpolation_options argument to resample method in Flight.
• extended documentation to include the new argument.
• extended the test case test_resample_how_argument to include a quadratic interpolation.

Before merging, please check if the documentation is sufficient and whether the intersphinx link to pandas is working, I did not test that.

Also please note that I set the flag check_exact=False for the test case because I had small rounding inaccuracies at 1e-6 and I was unsure if they are deterministic.

Thanks!