fischertechnik pneumatic manual valve with added connectors

The pneumatic line of the [fischertechnik](https://www.fischertechnik.de/en) construction toy system has a [manual valve](https://ft-datenbank.de/ticket/3225) which unfortunately does not allow any connections with standard fischertechnik parts like building blocks or axles. Thus, they are confined to manual usage.

This design replaces the blue part of the valve and enables a direct connection with standard fischertechnik building blocks or clip axles. Be warned that you'll have to take apart