* Combines VCF records from Beagle (v4) VCF and Pre-Beagle VCF files.
 * 	a child of GATK combineVariants to combine Beagle and Pre-Beagle
VCF, taking priority of Beagle VCF, but add attributes from Pre-Beagle
VCF to it.
change private/protected functions/variables to public/protected