inclusion of 'D raw' calculation

[JRodrigoF]

I'm interested in calculating linkage disequilibrium in its 'non-standardised' form, which in literature is often referred as simply D. I have done it using your LDBlockShow tool from VCFs and I think other people might want to have these estimates as well, besides D' and r2. I've made some additions to your repo so that it includes this option, probably needs further changes that you may add/correct on top, or that I am happy to do if you point me to. I refer to D as "D raw" here