gene-based columns

[brentp]

clinvar_gene_phenotype is not available in vcf2db. We can make this available by adding a new flag used as:

--aggregate chrom,gene:clinvar_disease_name:clinvar_gene_phenotype

which will aggregate the column clinvar_disease_name by chrom,gene and add a new column clinvar_gene_phenotype of type TEXT joined by os.environ.get('VCF2DB_JOIN', '|')

that can be specified multiple times.

This will store a dictionary and do an update at the end.