Unification of boundary conditions into one file.
Some changes to input file for reference cases. This should have been
done in another branch but I wanto to commit to save progress and I
don't want to deal with tswitching branches right now, I'm very busy
watching Futurama.
Files and types with 'Cyl' have been changed to '2DCyl' to better
differentiate between the two types of 2D geometry.
Solvers for charged and neutral particles in 2D Cartesian space.
Added solveds for 1D neutral particles (this branch is not the place to
do it, but it was a minor change).
User Manual updated with the new accepted options.
