functionality to update beamformer weights are what is left in
`update_weights`. The ability to update from a file is still needed but
should be provided as a way to populate memory and then call
`update_weights`

currently a call to init beamformer, with the `weights_h` set, without a
call to `update_weights` will lead to bogus results that would be hard
to identify. Need a way to safely know weights have been applied (or
not).