coincidence window width is required for RFS

[KrisThielemans]

randoms-from-singles needs to know the coincidence window width. The TOF PR introduced

STIR/src/include/stir/ProjDataInfo.inl

Lines 171 to 176 in e8f2dd8

	ProjDataInfo::get_coincidence_window_in_pico_sec() const
	{
	return scanner_ptr->is_tof_ready()? (scanner_ptr->get_max_num_timing_poss() *
	scanner_ptr->get_size_of_timing_pos())
	:(scanner_ptr->get_size_of_timing_pos());
	}

but this only works for TOF-ready scanners.

Of course, we don't know the width for most scanners currently in STIR.

Luckily, RFS is currently only used for GE scanners. The GE RDF data-format does store it (even before they had TOF)

STIR/src/IO/GEHDF5Wrapper.cxx

Lines 334 to 337 in e8f2dd8

	const int posCoincidenceWindow = read_dataset_int32("/HeaderData/AcqParameters/EDCATParameters/posCoincidenceWindow");
	const int negCoincidenceWindow = read_dataset_int32("/HeaderData/AcqParameters/EDCATParameters/negCoincidenceWindow");
	const float coincTimingPrecisionInPico = read_float(file, "/HeaderData/AcqParameters/EDCATParameters/coincTimingPrecision") * 1000; // in nanoSecs in file
	const int num_tof_bins = posCoincidenceWindow + negCoincidenceWindow + 1;

I guess at the moment we can only throw an error if the data is not known.