VCF 4.2 compatibility

[b-schubert]

It would be great to generalize the variant reader to VCF 4.2:

Possible problems:

• Different annotation tools use slightly different annotations in the comment column
• Check that for at least SnepEff, and VEP
• Annova still does not support direct VCF 4.2 input

[b-schubert]

@mwalzer Do you know if pyVCF can use the annotation coming from SnepEff and VEP?

[b-schubert]

see PR #184

[mwalzer]

I did not test VEP specifically, but pyVCF can do 4.1 for now, also from files of SnepEff.