Changes in D16 macro suggested by Stef to handle correctly the case where a Cd is given, but not an empty cell measurement

Issue 33: Added Salsa tests, including first files produced in 2004. rdid modified to handle the older Salsa files

Issue 33: First try to have a complete set of tests to check the data reading for the whole instrument history. Done for IN16.

Urgen correction for error in reading old IN16 data (elastic scan + PSD case). Will need further checking and adding unit tests, ideally for all instruments

Modifications by T. Saerbeck to polarized treatment, adding a calculation and output of spin asymmetry

Issue 32: Changes to use attenuation_coefficient value read from D11 NeXus file instead of hard-coded table

Repair silly error due to an extra sort that is not needed and was mixing wrongly the information when the scanning variable was not in increasng order

Changes to integrate and straight routines to handle better the needs for Salsa, including the hexapod scan (where datp.z is a string array)