src/commands.sh: add creation of meatagene and gc content figure for readthrough, readthrough_ctcf and no_readthrough exon list

src/commands.sh: modification of metaexon file of exons regulated or in a gene containing exons regulated by DDX5/17 near or Far from CTCF

src/commands.sh: change gc content figure -e parameter to 2000 + coverage figure for 5y only on expressed genes