move VCF reader classes to _deprecated module (based on deprecated CSV readers)
default db action add --> add_ignore_existing
model change: make isAutosomal nillable
aggregate variant data
Merge pull request #407 from dennishendriksen/testing

VCF to pheno converter (variant_gonl.xml) + variant aggregation
Merge branch 'testing' of https://github.com/molgenis/molgenis_apps
add final statement in order to close writer correctly