A tiny python script, update on fiberdesk 5 & 6 and tutorial

Python reader for BPF files saved by fiberdesk has been added to the download package.

It reads a BPF file and displays the field and spectrum vs. propagation.

Tutorial 5 on a short pulse oscillator was enhanced with more details.

Some bugs have been removed:

- the directory of files in a multi-element propagation was not recovered in some cases

- menu elements of multi-element propagation did not work

- rate equations unabsorbed pump power did not consider all pump wavelength

New version for fiberdesk 5 & 6 have been uploaded.