dge_workflow: future improvements

Whilst https://git.mpi-cbg.de/bioinfo/ngs_tools/blob/master/dge_workflow/featcounts_deseq_mf.R works well, it was developed a long time ago and some of the DESeq2 functionality and best-practices changed. So did what we might want to add or remove from the script.

In here we should list the things that we would like to change if we consider creating a new script for analysis.