DevonDeRaad/SNPfiltR: v1.0.1 - bug fixes

Summary of new changes: I fixed multiple bugs that resulted from lack of coverage of some possible idiosyncratic input vcf formats, and added additional internal checkpoints to try and catch issues with input vcf format not conforming to the expectations of the functions. Functions should now be much more likely to throw an informative error if vcf format is different than expected, rather than silently mischaracterizing genotypes internally. Specific details of bug fixes correspond to SNPfiltR issues #1-3. The last thing I did was increment the package version 1.0.0 -> 1.0.1 for CRAN re-submission.