delete tmp files immediately after use, some other improvements
delete tmp files immediately after use, some other improvements

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