include more beam weights

[joslloand]

Zotter conveniently offers a variety of additional beam weights here:

Ultraspherical/Gegenbauer polynomials to unify 2D/3D Ambisonic directivity designs

Three* beam weights don't include additional parameters, they could be added to HoaOrder: -beamWeights, and would integrate into the beam weight / beam forming functionality currently implemented.

• [ controlled ]
• [ energy (max-rE) ]
• maxFBR (superCardioid)

*[ controlled and energy are currently implemented via recipes from Daniel ]

A further two beam weights require a parameter adjusting acceptance angle so would require an update to HoaOrder: -beamWeights, or possibly a separate method. (See: #129)

• maxFlat (Zotter-Butterworth)
• sphereCap

[joslloand]

Example coefficient generation in sc-lang can be found here: Zotter_G_SC3_Code_examples.scd

[joslloand]

Other possible filters to consider may be found:

• Understanding filtering on the sphere : experiences from filtering GRACE data, Devaraju, Balaji, Table 3.1, p. 35
• spaudiopy, Chris Hold, spaudiopy.sph, sph.py