Cryptic error messages

[DavidSagan]

Right now error messages do not reference the lattice element where the problem occurred. This complicates tracking down errors. One thought: Pass along the lattice element name or (identifier) along with the other lattice parameters.

[mattsignorelli]

Good idea. We should pass the element name and also the BeamlineParams group, because this will give both the element index, the beamline, and later for RF tracking we may need to get bl.line[end].s_downstream which is gettable from this parameter group