Performance oriented rewrite of BatchSourceFile.
Performance oriented rewrite of BatchSourceFile.

shaves for me 2-2.5 minutes off the time to run "ant test.suite" from
locker.


martijnhoekstra/scala,felixmulder/scala,shimib/scala,felixmulder/scala,shimib/scala,slothspot/scala,lrytz/scala,felixmulder/scala,shimib/scala,martijnhoekstra/scala,slothspot/scala,slothspot/scala,martijnhoekstra/scala,jvican/scala,shimib/scala,slothspot/scala,martijnhoekstra/scala,martijnhoekstra/scala,lrytz/scala,felixmulder/scala,slothspot/scala,jvican/scala,martijnhoekstra/scala,slothspot/scala,shimib/scala,felixmulder/scala,lrytz/scala,felixmulder/scala,slothspot/scala,jvican/scala,scala/scala,scala/scala,lrytz/scala,lrytz/scala,jvican/scala,scala/scala,scala/scala,scala/scala,jvican/scala,jvican/scala,shimib/scala,felixmulder/scala,jvican/scala,scala/scala,lrytz/scala