Minor ColumnVCFInfo fixes (Export VCF info)

[davmlaw]

This should be upper case?

ID=gnomAD_HOM_ALT,number=.,type=I,descr: Count of homozygous individuals

Description is wrong:

##INFO=<ID=OVERLAPPING_SYMBOLS,Number=1,Type=String,Description="MaxEntScan percent diff/ref">

These should probably have GNOMAD in front of them?

ID=SV_overlap_AF,number=1,type=S,descr: gnomAD SV (StructuralVariantOverlap): frequency of overlapping SV
ID=SV_overlap_coords,number=1,type=S,descr: gnomAD SV (StructuralVariantOverlap): coordinates
ID=SV_overlap_name,number=1,type=S,descr: gnomAD SV (StructuralVariantOverlap): name of overlapping SV
ID=SV_overlap_PC,number=1,type=S,descr: gnomAD SV (StructuralVariantOverlap): percent of input SV covered by reference SV