Use potentially larger memory GATK HaplotypeCaller settings for VCF merging to handle large population files
Merge branch 'master' of https://github.com/chapmanb/bcbio-nextgen
Remove matplotlib and statsmodels dependencies from requirements to give updates a chance to install via conda
Avoid symlinking files, preferring to merge in batches with bamtools when necessary to avoid both line length issues and open file handle limits. #166