Commit breaks example

[CedricDViou]

Commit c4043b8 breaks example https://nenupy.readthedocs.io/en/latest/simu/beam_simulation.html#mini-array-response.

ValueError: shape mismatch: value array of shape (3, 12, 196608) could not be broadcast to indexing result of shape (12, 3, 196608)

class _AntennaGain getter doesn't return the right shape anymore.

[AlanLoh]

Thanks Cedric, I did struggle a bit with that, Emilie had other issues as well. I've added several tests to hopefully cover all possibilities.

[CedricDViou]

Thanks a lot for looking at this.