In each iteration, number of collisions are calculate as a REAL variable
(collFrac) and stored in each cell. The number of collisions is
calculated as FLOOR(collFrac) and, if it is >1 collisions are computed
as usual. Per each collision calculated, 1.0 is removed from collFrac
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.
