norm remove dupes doesn't handle symbolic and non-symbolic duplicates

Start with the norm/remove-dupes behavior described in this issue and compare the two supplied VCF records, then review the related context in issue #2182. Done means records representing the same underlying mutation are recognized as duplicates when one uses a symbolic representation and the other does not, with behavior verified against this example.

Hi, I discovered this while testing #2182 - it wasn't covered in the initial issue, so raising a new one

Norm/remove dupes doesn't handle a VCF with 2 records that refer to the same underlying mutation, but with symbolic and non-symbolic representations.

Example:

##fileformat=VCFv4.2
##FILTER=<ID=PASS,Description="All filters passed">
##INFO=<ID=END,Number=1,Type=Integer,Description="Stop position of the interval">
##INFO=<ID=SVLEN,Number=.,Type=Integer,Description="Difference in length between REF and ALT alleles">
##INFO=<ID=SVTYPE,Number=1,Type=String,Description="Type of structural variant">
##contig=<ID=NC_000003.11,length=198022430>
##reference=file:/data/human/hg19.fa
#CHROM	POS	ID	REF	ALT	QUAL	FILTER	INFO
NC_000003.11	128204048	.	GAGGAGATCAGGGAGCCATCGAAATCCCAAGATCAGACTGATTGAGTTAGAGACCCAGATTCCTTAATGGTCTGGAACCTCCGGAGTGCCTGAAACATGCACACACAACATGCACACAGACACACGTATACACATGCACACACGCTCCCAAACACATGCACATACAGAGTCACTTCCCTCGCTTCACATACTAAGTCCTGAGGTGGCTTGAATTTTCACTTAAGATTCAGGGAGGGAAAGGGGGAATTCCTGTTCTATGTTCTGGTCAGGCAGTGACCAACCCTGGGGCAAGGAACTGAACTTTGGGGGTACACTGGAAGCACTTAAGAAAATGGCAAAAGTTTTAGAGTCTCCTCTCCCTGACCCGGGGGTCTCAAACATCTGCTGGGGGCTATTAGAGCGAGACATCACCCATCCCCAGATCTGGGAAACCAACACTGCCACCTCTCCCAAGTCACAGCTCCCCACCACAAAAACGCAAATGCTCCCCTCTTCCACGAAGTCCCCAGCACCTGCCTTTACCTGAACAGGAACGAGCCTTGCTGCGCTGCTTAGGGGTGAAGCTGGAGGCCGGTCCCCCCAGGAAGCCTCCGGGGTGGAAGAGTCCGCTGCTGTAGTCGTGGGCAGCCGCCGGCACATAGGAGGGGTAGGTGGGGATGGGGTGGTGTGTAGCAGGCTGGGTGCCCATAGTAGCTAGGCCTGGGCGCAGGGGACTGCCACTTTCCATCTTCATGCTCTCCGTCAGTGACACCTGGTACTTGACGCCGTCCTTGTCCTCTCCTCGGGCTGCACTACCCCCCGCGGAAGATGAGGCTGGAGACGCAGCCCCCGTGGTGCTAGGGTCAGGAGACACTTCTTTGGGTGGCGTGGGTGGGAAGCCGAAAAGGTGGGAGCCAGAGTGGGCTGCTGTAGGGGTGAGGGAGGCCACTGAGCTCCCGCTGCCTCCCCCGCTCCCACCCCCAGCCCCTGGGTACACAGAGAGTGGGCCTCCAGGGCCTCCAGCAGCTGAGGGGTGCAGTGGCGTCTTGGAGAAGGGGCTCACGGTCCAGGGGTTGTGGTGGTGGGCCGCAGCGGCAGAGAGGGCTGCTTTGCCCCCGTCCAGCCAGGGCAAACCCGGGCTGTGCAACAAGTGTGGGCGGCACATCTGGCCTCCGGTCAGGCGGGCTGCGGGCAAAGAGAGAGAGGATCAGGGTGGGCAGAAAGATCAGGGTAGGCAGAGCTAGGGACGCCCCTGACAGACATTGAGATCACGACTCCCAGAACCAGCAGTCATCCCCTCCCCAAAGAAAGCCAGAAACATAATACCCCACCGGTAATAATCAGGAATGTCAGTCCAAGCTGAAGGACAAGTGGCATAGAAGGAACCCCACCGGACAGACCCTACAGGGAACCCTCACAGGCCAGCTGGAAGTGGGCAGAAACCCTGTGGGTCCCAGACCCTCCCCAATCGGCCGCTGCTCCCACCTCTCCCGCCCCAATTTTTCAGCAGCTCGATTCCTGCGGATCCTACATCCGGGAAGCAAGCAGACGGGCCCTCCTCCCCTCCCTCGCCTGGCGCGCGGCGCCTGGGTTCTCATCACCACGGGCCCAGTGCTCACCGTGCGCGGGGCTGTAGGAGACGCGCGCCCGCGCGTGAGCGGGGTTGGCATAGTAGGGGTTGCCCTGCGAGTCGAGGTGATTGAAGAAGACGTCCACCTCGTCTGGAGGCAGCAGCTGCGCGGGTTCCATGTAGTTGTGCGCCAGGCCCGGGTGGTGTGAGTCGGGGTGCTGCGCATTCAGCACGGCCGGGTGCGCCATCCAGCGCGGCTGCTCGGGCGCCACCTCCATGGCCGGCGGCGGCGGCTCAGGGTCTGGGTGCAGACGGCAACGGCCCTGCGCGAGGAAGGGGGAGTGAGGCGTGCCGCCAGCGCCTGACACCCCCCAAAGTCCCACCACGAGGTGTCCCGCACGCCACGGAGCCCCAGCCCAGATCCGGCGAGAAAGAGCACCAGTCCCGGGTGGGAGGAAAGCCCAAGGCTCAAAACGAAAGGAAGGCGGGGGAGGGGGTTCAGCCACGCACACTCACGTGGTGACCCGCGGCTCCAGAATCACACACCCGTGCACATGGGGTCACGCCCGGGGACGGGTCCCGACACCAGTGACCCCAACAAACGCACAGAGCAGCACTTCAGTCAGACACTCACACTGAGCCCCCCCGCCCGGTAGACAAACACATGAACACAGACTCAAAAGTTGGAGACAGGCGCCCGGGCACCCAGTGTGGCACTTGATCCCAGCGACACGCACACACCCACACTTGGCGCCAGATACACATACTGATCTCAACCCCGAAAACATGCACACGCAGCCCCCTGAGCGCAGTACTAAGCGGCACAATCAGGACCTCTCAACAAAGCACACCAAAGCAGTCGCCCGCAGCCTGGCCCCCCGCCCTAAGTCCCCCCAGAGTCCCCTCAAAGCTAGGAGCGCCCCAGGCCCCCAGCCGGCTCTCAAACCCCAAACTTACACACGCAGCCGTGGGGAGGGGAGGGACTCGGCCTCTGAGAGTGAAGGAGTTCCGGCGGGAGCCCCGAGGGCGACGGGCCCAGGGACAGCACGTCCGGAGGCTGGCGGGGCTTACAGGGTAGGAGCTGGGGGTAGAGTGCGCCTCGGCCTCGGGCCCTCCCG	G	.	PASS	.
NC_000003.11	128204048	.	G	<DEL>	.	PASS	END=128206714;SVTYPE=DEL;SVLEN=-2666