Bug fix for windowed fst function

git-svn-id: https://svn.code.sf.net/p/vcftools/code@944 19d466ce-640d-45be-954f-fad4d9839663
Edit version number for patch

git-svn-id: https://svn.code.sf.net/p/vcftools/code@945 19d466ce-640d-45be-954f-fad4d9839663
vcf-sort: -p to change the number of sorts run concurrently

git-svn-id: https://svn.code.sf.net/p/vcftools/code@946 19d466ce-640d-45be-954f-fad4d9839663
Merge remote-tracking branch 'upstream'