Parameters read by smoothing_cxx:

fwhm_arcmin (double):
  FWHM (in arcmin) of the Gaussian beam used for smoothing. If the value
  is negative, the smoothing of a Gaussian beam with an FWHM of -fwhm_arcmin
  will be _removed_ from the input map.

nlmax (integer):
  maximum order of l

infile (string):
  input file containing the Healpix map

outfile (string, default=""):
  output file for the smoothed Healpix map

polarisation (bool):
  if false, only an intensity map is smoothed
  if true, an IQU map is smoothed

weighted (bool, default=false):
  if true, weighted quadrature is used

if (weighted)
  healpix_data (string):
    directory containing the Healpix data files
endif

iter_order (integer, default=0)
  number of iterations for the analysis (0: standard analysis)

double_precision (bool, default=false):
  if false, a_lm are read/written in single precision, otherwise in
  double precision.
