1. Modified vcf_parse to update rlen only when an END INFO tag is seen -

Issue: https://github.com/broadinstitute/gamgee/issues/191
1. Modified vcf_parse to update rlen only when an END INFO tag is seen -the END tag is NOT encoded into v->shared.s
2. Modified vcf_write to add END INFO tag if required

The check we discussed is the one you are already doing. If the difference between the ref and any of the alleles is equal to rlen, then this is not a block. Otherwise, it is a block. Is this right @jmthibault79 ?