nxflatfield: update order of load of computed dark and flats.
- first: default location defined by tomoscan (flats.hdf5 and darks.hdf5 for HDF5Tomoscan, dark.edf and flatHSTXXXX.edf for EDFTomoScan)
- second: look on tomwer_processes.h5 (to insure backward compatibility)
- third: look on nabu_process.h5 (for backward compatibility)
Edited by payno