Benchmarked improved coroutine model.

Average speedup: 17.9.
Added new benchmarks.
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
code format
Change to one of the benchmarks; report on measurements done with
a faster machine (mac mini) and several subsequent runs.
Merge branch 'master' of https://github.com/cwi-swat/rascal.git
Inlined MATCH and MATCH_DESCENDANT as calls and removed them from the
Library.mu.
Made another run of benchmarks: visits seem to be a bit faster.
Rewritten bencmark framework to give better control over execution order
Some cleanup/commenting of benchmarking framework
Removed some unused local variables
Merge branch 'master' of https://github.com/cwi-swat/rascal
Aded severals series of measurements, new approach increases
reproducibility
Merge branch 'master' into rascal-to-jigll