New material for pipes: Polypropylene

As of the 2020.e version, users can define pipes in "CYPEFIRE Hydraulic Systems" that are made out of polypropylene.

This material has a table of nominal diameters that is different to those of the other materials that are included in the program. Therefore, once a pipes catalogue has been generated with this selected material, it will not be necessary to change the material of the catalogue.