pigx-rnaseq now depends on megadepth

[Steffen Möller <steffen_moeller@gmx.de>]

I was not aware of megadepth - but that is why to pick some experts'
workflow system in the first place as a reference.

https://salsa.debian.org/r-pkg-team/r-bioc-megadepth

needs

https://salsa.debian.org/r-pkg-team/r-cran-cmdfun

and I am still working on the megadepth binary that is wrapped. So, for
the moment this needs to be installed independently. I suggest to
nonetheless upload the package already.

I would love to see the package(s) reviewed.

Many thanks

Steffen