Roadmap meta-issue

Towards the first version tag:

TODO:

• Implement Amiet amplitude correction
• Implement shear layer correction based on ray casting
• Find bottlenecks in code with TimerOutputs.jl
• Signal processing method for calculating cross-spectral matrix
• Faster CSM using DSP.jl. Implement a csdand csdm method.
• Covariance-Matrix-Fitting method with warm-start (see if it can be speeded up somehow)
• FISTA prox
• FISTA with backtracking: https://github.com/klkeys/FISTA.jl/blob/0937f0d215fb982e59fbefe50717628173910c30/src/lasso.jl#L67
• Refactor steeringvectors to dispatch only on steering vector type not environment, e.g. Shear() or Uniform()
• Remove dependency on HDF5 and make user input time-data or csm arrays.
• Move to lazy operators for beamforming, PSF etc.