Extend BOLSIG+ functionality

[daanboer]

The current BOLSIG+ interface is quite minimal, the input form contains a subset of the available input options, and the output only shows the computed electron energy distribution functions.

• Add plots for different outputs (reduced mobility, reduced diffusion coefficient, rate coefficients, etc.).
• Extend the input form to support list more of the available input options. The available input options are listed in the BOSLIG+ documentation: https://www.bolsig.laplace.univ-tlse.fr/manual.html.
• Add a download button to download the results of a simulation.
• Provide a permalink that points to the exact simulation tool version, input parameters, and data used to run the simulation.

Some additional comments by Leanne:

• In my opinion, it would be easier if you pose the question "Coulomb collisions, yes/no" and if "yes", then (and only then) the users must specify ionization degree and plasma density. Those parameters aren't useful except when Coulomb collisions are taken into account, as they should be if the ionization degree > 1.e-5.
• The boxes under the choice of spacings for E/N need labels.
• I don't think it's necessary to give users a choice of grids for the version of BOLSIG+ incorporated in LXCat. In any case, it should be stated that additional options (grid size & spacing, B fields,...) are available in the downloadable version of B+.
• References are needed for the Boltzmann solver.