basic restore of original read_coverage code
basic restore of original read_coverage code

at7/ensembl,james-monkeyshines/ensembl,mjg17/ensembl,danstaines/ensembl,mjg17/ensembl,danstaines/ensembl,muffato/ensembl,mjg17/ensembl,Ensembl/ensembl,james-monkeyshines/ensembl,Ensembl/ensembl,muffato/ensembl,mjg17/ensembl,Ensembl/ensembl,Ensembl/ensembl,at7/ensembl,at7/ensembl,muffato/ensembl,at7/ensembl,muffato/ensembl,james-monkeyshines/ensembl,james-monkeyshines/ensembl,danstaines/ensembl