Starting the work on SN.
Making linear-advection-dg-adapt the basis for the SN solver.
Disabling adaptivity.
Single-direction SN example.
Multiple directions.
Updating to new API.
Implementing the source-iteration algorithm as a special case of the Picard-iteration.
Virtualizing the destructor of NonlinearSolver.
Updating the debug output in neighbor.cpp
Update of the SN-first_attempt example.
Adding the DRAGON input files to SN-first_attempt.
Adding the SN option to the NeutronicsMethod.
SN version of MaterialProperties and SupportClasses.
Updating to the new API.
Minor correction in neutronics support classes.
Placeholders for OpenMP functions for the case WITH_OPENMP = NO.
Deleting some old files.