added some code to deal with non-chaining mapping sessions
added some code to deal with non-chaining mapping sessions

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