minor changes  to shbasis
minor changes  to shbasis

Main changes are:

- limit lmax to 8 - higher orders are generally noisier, and if the
  information is not sufficient by that stage, adding higher orders is
  unlikely to help. In certain datasets, it actually makes things
  worse...

- get overall ratio as ratio of overall power in m=0 vs. m!=0 terms
  over all SH degress, rather than averaging the ratios computed per SH
  degree.

- output ratio per SH degree along with power in m=0 term using INFO()
  rather than DEBUG() for a cleaner, yet still informative output with
  -info.

MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3,MRtrix3/mrtrix3