New module: vartrix

[stela2502]

Vartrix (https://github.com/10XGenomics/vartrix) is a tool to quantify single cell SNP data. As it is not available here I think it would be a good idea to get it. This should be horribly simple to make this work as there is already a BioConda package for the tool. I do not plan to create a perfect module, but a first working 'example' to in the end create a package that performs lineage tracing using mitochondrial mutations. A first search here did not show a previous request.