Ancillary items from Bio-SamTools

Created by: drjsanger

@keiranmraine created a ticket on the perviously copied repo, so I'm reopening it as it's been lost.

bam2bedgraph is missing, however Bio-DB-HTS also doesn't include the utility perl scripts that use it. I have written an htslib dependant version of bam2bedgraph (NB the input style is slightly different). Should you choose to include it you can find it here:

https://github.com/ICGC-TCGA-PanCancer/PCAP-core/blob/dev/c/bam2bedgraph.c