implemented the $vc->extend(n,n) method
implemented the $vc->extend(n,n) method

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