'Add an InvSampler, and an example JO for flat field curvature and beamline IP sampling. Plus some more general code tweaks.' (ParticleGun-02-01-00)

	* Tagging: ParticleGun-02-01-00

	* Add an example JO showing how to use the inverse sampler to
	sample flat in B-field curvature and how to couple together
	momentum and position sampling to give an impact parameter
	distribution.

2016-04-05  Andy Buckley  <andy.buckley@cern.ch>

	* Explicitly force more sampler constructor args to float type.

	* Add InverseSampler, for e.g. B-field curvature ~ 1/pT.