Resolve "Probe does not register all particles"

Closes #375 (closed)

The width of the probe and stripper is adapted per particle and not longer based on the average bunch. This will fix the issue, but will be computationally a bit more expensive (though to be seen, there is a reduce call less).

There remains some duplication between Stripper and Probe and there could be some more optimisation to improve the calculation speed, but this will come at a later point. The changes right now should allow @frey_m to continue his work.