hacked in support for multiple phasespaces for measuring energy spectra, forwards and backwards without fstops
added cuts setter/override
Should have been calling PhysicsHasBeenModified, but that is not requried here?
initialised default values for cuts
using standard physicsl list, option 1
optional killing at a phasespace, kill=false is useful if you just want info at a plane, but do not want to resimulate from there