* Build `+RTS -A256m -RTS` into default ghc-options for benchmark,
so we don't have to specify this separately on the command line.
This is necessary to get accurate benchmark results; otherwise
we are largely measuring garbage collecting, some not related
to the current benchmark.
* Switch back from gauge to tasty-bench.
* Allow specifying BASELINE file in 'make bench' for comparison
(otherwise the latest is chosen by default).
* Remove obsolete reference to weigh-pandoc from CONTRIBUTING.md.
* Remove `-Rghc-timing` from 'make bench'.
John MacFarlane
c6e5cf2e74