Z50 and Z60 cogwheel for fischertechnik

Two types of Z50 and Z60 cogwheels for use with fischertechnik. The cogs will mount with the regular nr 31014 or 31015 hubs to a 4mm axle.

To make it easier to print without support, I also added the models with one flat, non-faceted side. Two faceted edges are only necessary when using fischertechnik chains anyway and it can be easily made by hand afterwards with a sandpaper (along the rotating gear) if necessary.