bcftools (BCF calling tools) contains all the "vcf..." commands which 
previously lived in the htslib repository (such as vcfcheck, vcfmerge,
vcfisec, etc.) and the samtools BCF calling from bcftools subdirectory 
of the previous samtools. BCFtools are meant as a faster replacement 
for most of the perl VCFtools commands.

Prior to the introduction of HTSlib, SAMtools and BCFtools were
distributed in a single samtools-0.1.x package. This old version remains
available from SBo as samtools-legacy.