Ribodesigner: verify the rRNA annotations

[khourhin]

rRNA annotation in gff files can be misleading. For example, for the mouse genome, in the Ensembl GFF annotation, the 18S ribosomal gene feature is "ncRNA_gene" (not rRNA, although the "rRNA" feature exists). We need to verify, depending on the annotation type (Ensembl/NCBI) how to actually get the main rRNA sequences