New option for initial distribution of species

The number of particles per cell can be defined when giving an initial
distribution fora species. If not, the typical method of using the
species weight is used. This is particularly useful for cylindrical
coordinates in which very little particles might end up in the axis if a
constant weight is used.

doc/user-manual/bibliography.bib.sav

@@ -0,0 +1,77 @@
+% Encoding: UTF-8
+
+@InProceedings{boris1970relativistic,
+  author    = {Boris, Jay P},
+  booktitle = {Proc. Fourth Conf. Num. Sim. Plasmas},
+  title     = {Relativistic plasma simulation-optimization of a hybrid code},
+  year      = {1970},
+  pages     = {3--67},
+}
+
+@article{higginson2020corrected,
+  title={A corrected method for Coulomb scattering in arbitrarily weighted particle-in-cell plasma simulations},
+  author={Higginson, Drew Pitney and Holod, Ihor and Link, Anthony},
+  journal={Journal of Computational Physics},
+  volume={413},
+  pages={109450},
+  year={2020},
+  publisher={Elsevier}
+}
+
+@Misc{gfortranURL,
+  author       = {GNU Project},
+  title        = {gfortran - the GNU Fortran compiler},
+  howpublished = {\url{https://gcc.gnu.org/wiki/GFortran}},
+}
+
+@Misc{ifortURL,
+  author       = {Intel\textsuperscript{\textregistered}},
+  title        = {Intel\textsuperscript{\textregistered} Fortran Compiler},
+  howpublished = {\url{https://software.intel.com/content/www/us/en/develop/tools/oneapi/components/fortran-compiler.html}},
+}
+
+@Misc{openblasURL,
+  title        = {OpenBLAS, an optimized BLAS library},
+  howpublished = {\url{https://www.openblas.net/}},
+}
+
+@Misc{jsonfortranURL,
+  title        = {JSON-Fortran},
+  howpublished = {\url{https://github.com/jacobwilliams/json-fortran}},
+}
+
+@Misc{jsonURL,
+  title        = {JSON, JavaScript Object Notation},
+  howpublished = {\url{https://www.json.org/json-en.html}},
+}
+
+@Misc{gmshURL,
+  author       = {Christophe Geuzaine and Jean-François Remacle},
+  title        = {Gmsh},
+  howpublished = {\url{https://gmsh.info/}},
+}
+
+@Article{welford1962note,
+  author    = {Welford, BP},
+  journal   = {Technometrics},
+  title     = {Note on a method for calculating corrected sums of squares and products},
+  year      = {1962},
+  number    = {3},
+  pages     = {419--420},
+  volume    = {4},
+  publisher = {Taylor \& Francis},
+}
+
+@Article{sherlock2008monte,
+  author    = {Sherlock, Mark},
+  journal   = {Journal of Computational Physics},
+  title     = {A Monte-Carlo method for Coulomb collisions in hybrid plasma models},
+  year      = {2008},
+  number    = {4},
+  pages     = {2286--2292},
+  volume    = {227},
+  groups    = {Particle-in-cell},
+  publisher = {Elsevier},
+}
+
+@Comment{jabref-meta: databaseType:bibtex;}