CLEAN Methods:

      CLARK       A minor/major cycle cleaning using FFTs for speed
                  Fast, but less stable than others.
      HOGBOM      The basic deconvolution method, working component per
                  component. Slow but robust
      MRC         A dual-scale multi-resolution Clean working on a smooth
                  and a difference map. Fast, but with no notions of Clean
                  components
      MULTISCALE  A 3-scales multi-resolution-Clean working on 3 smoothed
                  versions of the map. Slow, but very stable and adapted to
                  sources with extended structures.
      SDI         A major-cycle only method. Good for extended structures
                  but not very performant overall.