second attempt to add the VCF exporter

The VCF exporter finally generates output that can be used in R.
When you say

> This exporter works with a client currently hosted at ...

Do you mean that the exported VCF will not work anything other than the client being linked to? That is, does the exporter put anything into the VCF that would require it to be opened with your client or could any normal client capable of importing VCFs process and VCF exported from this exporter.