Geant4InputHandling: create G4PrimaryParticle with 4 vector that constrains also the mass, setting the mass after, affects the momentum

this worked accidentally in python2, but now the dictionary order is fixed and isotrop was set to false when parsing the default values, because it happens after the setting of distribution now

This reverts commit cd161772.

This reverts commit bea8748c.

- Avoid duplicates in paths
- Support whitespace in paths
- Don't add system paths to library paths on macOS