TrkGlobalChi2Fitter: Cleanup of the GlobalChi2Fitter code

Here's a bit of a large merge request, but it's not as scary as it looks. Most of the changes are in 28d0af77 which should be purely syntactical; it contains a manual effort to make every single file in the GlobalChi2Fitter code base properly formatted and readable. For the rest, this merge request removes a largely redundant class (made redundant by a several past changes to how the fitter works) and a bunch of data members.