Autocorrclean

[hmuellergoe]

Major code in this request:
-> Implementation of autocorr-CLEAN

includes also a few, minor updates and some experimental code for other methods:

• option to work with odd number of pixels in Asp-CLEAN
• expose LBFGSB quantities (tolerances, exit criteria) to the top level
• expose scales for Asp-CLEAN to the top level
• add an option to never switch to Hogbom in Asp-CLEAN when fusedthreshold is set to a negative number
• experimental code for approximating the psf as a sum of wavelets, to accelerate Asp-CLEAN LBFGS computation (that is like the Zhang version, but instead of a simple Gaussian approximating the main lobe, we use a few Gaussians approximating the main lobe and the first few sidelobes), not robustly tested yet
• experimental alternative multifrequency Asp-CLEAN option: in which the Asp's are defined from a continuum image. Then the spectral imaging bypasses the iterative CLEAN part of Asp-CLEAN, simply reads in the continuum Asps, and for every spectral channel just solves the LBFGSB step (i.e. adapts the Asps locally to what is needed in a respective spectral channel), not robustly tested now
• added options to save and load helper products