comments/formatting
Remove outdated comment

the loop2 driver is much, much better now that some other functions
have had their INLINING tuned, and leaving it un-INLINE'd is
unambiguously better.
Stream.hs: add Monad instance
WIP: delimited-stream support for hylo
initial benchmarks for delimited-stream support

Not fair yet, because initStream isn't a full delimitG, but looks
promising.
I'm not convinced that the implementation (or approach) is optimal.