Enhancement request: enable use with VCFv4.2

[jennaj]

sequence_utils/galaxy_utils/sequence/vcf.py

Lines 63 to 64 in 3112094

	class VariantCall41(VariantCall40):
	version = 'VCFv4.1'

VCFv4.0 == ok
VCFv4.1 == ok
VCFv4.2 == tool fails with

https://usegalaxy.org/u/jen-galaxyproject/h/test-vcftomafcustomtrack1

            Traceback (most recent call last):
  File "/cvmfs/main.galaxyproject.org/galaxy/tools/maf/vcf_to_maf_customtrack.py", line 192, in <module>
    main()
  File "/cvmfs/main.galaxyproject.org/galaxy/tools/maf/vcf_to_maf_customtrack.py", line 108, in main
    vcf_files.append(PopulationVCFParser(galaxy_utils.sequence.vcf.Reader(open(filename)), pop_name))
  File "/usr/local/lib/python3.7/site-packages/galaxy_utils/sequence/vcf.py", line 111, in __init__
    self.vcf_class = VariantCall.get_class_by_format(metadata_value)
  File "/usr/local/lib/python3.7/site-packages/galaxy_utils/sequence/vcf.py", line 15, in get_class_by_format
    assert format in VCF_FORMATS, 'Unknown format type specified: %s' % format
AssertionError: Unknown format type specified: VCFv4.2

[nsoranzo]

The latest version of the VCF format is 4.5, if anyone is interested in fixing this the differences among the various VCF version are listed at the end of https://samtools.github.io/hts-specs/VCFv4.5.pdf