Exuberent tags were confusing vim

Actually, vim was fine, until you hit a tag that came from a source
line with a non ascii character. Then it got into a terrible muddle.
Use Builder when serializing Request and Response

Convert to use of blaze-builder when composing Request and Response
bytes for transmisison, instead of S.concat.

Profiling was ambigious; the allocation was the same regardless of
which technique is used, but the code is equivalently simple and may
be faster.
Remove warning suppression
Remove unnecessary imports
Fork Benchmark to ComparisonBenchmark

As with Snippet, copy Benchmark.hs to a static name so we can (re)use
the benchmark target for work-in-progress.
Rename Snippet and Benchmark files
Rename benchmarks
Copyright year update