Make benchmarks compile with older bytestring
Improve performance by using specialized parser combinator

The new combinator is specialized to detecting things seperated by
newlines.

The results are modest, but positive:

Name	Mean
positional/decode/presidents/without conversion            96.55%
positional/decode/presidents/with conversion               94.36%
positional/decode/streaming/presidents/without conversion  99.30%
positional/decode/streaming/presidents/with conversion     91.39%
positional/encode/presidents/with conversion               96.40%
named/decode/presidents/without conversion                100.25%
named/decode/presidents/with conversion                    94.10%
named/encode/presidents/with conversion                    96.18%
comparison/lazy-csv                                        93.81%