FT_SOURCEDESCRIPTIVES computes descriptive parameters of the source
 analysis results.

 Use as
   [source] = ft_sourcedescriptives(cfg, source)

 where cfg is a structure with the configuration details and source is the
 result from a beamformer source estimation. The configuration can contain
   cfg.cohmethod        = 'regular', 'lambda1', 'canonical'
   cfg.powmethod        = 'regular', 'lambda1', 'trace', 'none'
   cfg.supmethod        = 'chan_dip', 'chan', 'dip', 'none' (default)
   cfg.projectmom       = 'yes' or 'no' (default = 'no')
   cfg.eta              = 'yes' or 'no' (default = 'no')
   cfg.kurtosis         = 'yes' or 'no' (default = 'no')
   cfg.keeptrials       = 'yes' or 'no' (default = 'no')
   cfg.keepcsd          = 'yes' or 'no' (default = 'no')
   cfg.keepnoisecsd     = 'yes' or 'no' (default = 'no')
   cfg.keepmom          = 'yes' or 'no' (default = 'yes')
   cfg.keepnoisemom     = 'yes' or 'no' (default = 'yes')
   cfg.resolutionmatrix = 'yes' or 'no' (default = 'no')
   cfg.feedback         = 'no', 'text' (default), 'textbar', 'gui'

 The following option only applies to LCMV single-trial timecourses.
   cfg.fixedori         = 'within_trials' or 'over_trials' (default = 'over_trials')

 If repeated trials are present that have undergone some sort of
 resampling (i.e. jackknife, bootstrap, singletrial or rawtrial), the mean,
 variance and standard error of mean will be computed for all source
 parameters. This is done after applying the optional transformation
 on the power and projected noise.

 To facilitate data-handling and distributed computing you can use
   cfg.inputfile   =  ...
   cfg.outputfile  =  ...
 If you specify one of these (or both) the input data will be read from a *.mat
 file on disk and/or the output data will be written to a *.mat file. These mat
 files should contain only a single variable, corresponding with the
 input/output structure.