Mostly cosmetic changes courtsey of our linting overlords

- SublimeLinter-cpplint suggestions, nothing of consequence
Introduce typedefs to shorten some type names

- const TLorentzVector&,
- const TVector3&
- vector<TLorentzVector>&
Refactor TDA analysis code - split into small funcs
Refactor TDA analysis code - split histogram defs into funcs
Cosmetic changes
Minor changes to pion beam optics macros
Modifs to pion beam optics code

Hbeam.h
- Add a profile to initial discrete random delP distribution so that
  enough events are generated for extreme delP values even after
  transmission
- Remove randomizer after hit positions are digitized on pion trackers
  and start detector
- Remove SET ERR on Minuit, which was setting it to default value
  anyways (value that determines what variation in par value is used to
  set errors)
- Experiments with fixing parameters for minuit fit (use TDR solution
  for part of the parameters)

pion_generator.cpp
- MS now only on pion trackers. Meaning of arguments for MS changed. XY
  means X->traker1 Y->tracker2 (used to be X->tracker1&2 Y->start) still
  under construction

plot_pres.C
- generate between delP = -5 and 5 (used to be -6 and 6)
- factor out histogram limit saving and retreiving, resulting in static
  histograms for easy access in refactored funcs
- cases changed for 4th pass (simplified a bit)
- X and Y resolution plot maxima independent now, set so that all points
  are visible in both plots. Margin changed so that axes labels are
  visible for the Y resolution plot
Fix inv. mass plot according to referee comment for Meson2014 proceeding