Possibility to input initial species distributions (density, velocity
and temperature) via an input file for each species.
New moduleRandom includes function to generate random numbers in
different ways (still uses) the implicit RANDOM_NUMBER().
Now collisions can have a different time step.
Added species name to output names as it was starting to get confusing
in Gmsh for multiple species.
Output filenames adapted to match any number of iterations.
Maxwellian and Diract Delta distributions have been implemented.
The input for injection of particles should be rewritten to allow more
clear input file.
