Using the bootstrapping option (--iters) adds an extra line to the output abundances file

[tmaklin]

If mSWEEP is run with the --iters option enabled, the output *_abundances.txt file will have an extra empty line at the end when compared to the *_abundances.txt file that would be produced without the --iters option. This extra line confuses some postprocessing tools like mGEMS, and the file format should be fixed so that there is no extra line at the end of the *_abundances.txt file.

I will add a fix as soon as possible.