VCF test case filenames should be more meaningful

[d-cameron]

Names such as failed_body_info_020.vcf are uninformative and imposes an unnecessary ordering on the test cases. Files should be renamed to be more meaningful (e.g. failed_body_info_H3_not_flag.vcf)

[d-cameron]

Also, should we have a category for lenient parsing of things that are technically non-compliant? E.g. DP=2.0 fails the integer regex but there's no loss of information if you parse it as a 64-bit floating point then cast to 32-bit signed integer.