gCNV adapter and track

[garrettjstevens]

There's some info about gCNV output files and a sample of what a track might look like here (sample is on IGV web): https://github.com/igvteam/igv.js/pull/1055 (sample reproduced below).

I think "gCNV output" is referring to the output of GATK's GermlineCNVCaller. Also possible relevant is the last plot on the XHMM page (also reproduced below):

[cmdcolin]

this seems like it would effectively be a "multi bedgraph"

see https://github.com/igvteam/igv.js/blob/master/test/data/gcnv/gcnv_large.bed.gz

it should work fine as an adapter to a multiquantitativetrack