Add history of relative efficiencies of D33 panels to reading routine

On 27/6/2018, Isabelle Grillo told me that now the relative efficiencies of all the D33 panels are the same. This is handled by the p2p1, p3p1, p4p1 and p5p1 variables in read_hdf.pro. It could be worthy to have a table of values for different dates in order to be able to read correctly both present and old numors.