seed not saved in the info file

[teuben]

in order to re-run mcluster with the same seed, the seed is only stored on stdout, but not in the info file.
I have a pull request on that coming up.
However, it then turns out that the ascii output file (the .txt file) has too many digits for double precision. Often the last 1 or 2 digits differ in two runs with the same seed.