M2365 As genotypeIO user I want efficient VCF reader for streaming and random IO

- MOLGENIS and Genotype-IO independent VCF reader
- VCF: Faster iteration over all variants
- Various performance improvements
- Introduce SampleVariantsProvider.getSampleGenotypeRecords
- Introduce GeneticVariant.getVariantMeta

See http://www.molgenis.org/ticket/2365