Request: option to recover the fitted flux, flux error, etc. in a TS map

[israelmcmc]

The TS map computes the best fit flux for each pixel (given a spectral shape). This information is returned by the solver pixe-by-pixel:

cosipy/cosipy/ts_map/fast_ts_fit.py

Lines 162 to 184 in 55db870

	def _fit_one_direction(self, source,
	data_cds_array, bkg_model_cds_array,
	psr_cache):
	"""
	Perform a TS fit of data for a single source direction
	Parameters
	----------
	source : np.ndarray
	source direction as Cartesian 3-vector
	data_cds_array : numpy.ndarray
	The flattened Compton data space (CDS) array of the data.
	bkg_model_cds_array : numpy.ndarray
	The flattened Compton data space (CDS) array of the
	background model.
	psr_cache : PSRCache
	Cache to retrieve PSR for source direction
	Returns
	-------
	result of TS fitting:
	[ts value, norm, norm_err, failed, # iterations]

but is then lost, since we only recover the TS:

cosipy/cosipy/ts_map/fast_ts_fit.py

Lines 317 to 320 in 55db870

	self._fit_one_direction(source,
	data_cds_array,
	bkg_model_cds_array,
	psr_cache)[0]

It would be nice for the user to obtain array for the rest of the value: norm, norm_err, failed, # iterations. This result can be output based on an optional flag in fit()