Fix the random number generator
As discussed in issue #545 (closed) the random number generator is Swift is currently poor. In this merge request I basically aim at solving the issue with correlated random numbers and make the random numbers uncorrelated and added two tests:
- First test checks if the random numbers are correlated in time.
- Second test checks if the random numbers are correlated in adjacent IDs at fixed times.
Let me know what you think of the code. I will do some final testing on the isolated galaxy to make sure everything works.
Edited by Matthieu Schaller