dge_workflow: expression_explorer app failed to load due to renamed/additional annotation columns

Issues:

• at least for the igenome Homo_sapiens/Ensembl_v99 (others were not tested) running featcounts_deseq_mf.R with the --gtf flag results in empty gene descriptions which have to be manually added; however, adding the information from biomaRt ensembl results in the column 'description' instead of 'gene_description' if not manually changed and this leads to issues with the expression_explorer app which assumes the 'gene_description' but not the 'description' column
• annotation columns (e.g. domain prediction) which are additionally added to the dge results are not taken into account when the columns for further data summarization are selected in the gather functions