Add livetime correction to get_data

[samaloney]

Add livetime correction option to get_data via keyword default to true.

Essentially extract, and modify/generalise this part and add to get data

stixpy/stixpy/calibration/visibility.py

Lines 195 to 219 in fb3004c

	trigger_to_detector = STIX_INSTRUMENT.subcol_adc_mapping
	# Map the triggers to all 32 detectors
	triggers = pixel_data.data["triggers"][:, trigger_to_detector].astype(float)[...]
	_, livefrac, _ = get_livetime_fraction(triggers / pixel_data.data["timedel"].to("s").reshape(-1, 1))
	pixel_data.data["livefrac"] = livefrac
	e_cor_high, e_cor_low = get_elut_correction(e_ind, pixel_data)
	# Get counts and other data.
	idx_pix = _PIXEL_SLICES.get(pixels.lower(), None)
	if idx_pix is None:
	raise ValueError(f"Unrecognised input for 'pixels': {pixels}. Supported values: {list(_PIXEL_SLICES.keys())}")
	counts = pixel_data.data["counts"].astype(float)
	count_errors = np.sqrt(pixel_data.data["counts_comp_err"].astype(float).value ** 2 + counts.value) * u.ct
	ct = counts[t_ind][..., idx_pix, e_ind]
	ct[..., 0] = ct[..., 0] * e_cor_low[..., idx_pix]
	ct[..., -1] = ct[..., -1] * e_cor_high[..., idx_pix]
	ct_error = count_errors[t_ind][..., idx_pix, e_ind]
	ct_error[..., 0] = ct_error[..., 0] * e_cor_low[..., idx_pix]
	ct_error[..., -1] = ct_error[..., -1] * e_cor_high[..., idx_pix]
	lt = (livefrac * pixel_data.data["timedel"].reshape(-1, 1).to("s"))[t_ind].sum(axis=0)