Initial Geant4 commit.
Basic implementation based on an example.
Fix indentation.
Generalize main. Add visualization.
Define the sun's material.
Use QGSP_BERT physics list.
Use density of the sun's core.
Use sphere for world geometry.
Output basic neutrino info.
Create basic abstraction for a histogram creator.
Add a preliminary histogram support.
Fix error on histogram creation.
Refactor main.cc
Add hook on run start (for verbosity).
Fix indentation in CMakeLists.txt
Add incomplete Pythia support.
Add statistics function to Pythia interface.
Create opposite dir/equal energy particle gun setup.
Add argument parsing and refactor main.cc
Fix vis flag.