First stab at making the recursivedisambiguation threaded.
Keep a global thread count.
Merge branch 'master' into threads
best_harmonic_mean.
best_harmonic_mean(): Make more generic.
best_harmonic_mean(): cleanup.
Merge branch 'master' into threads
Remove traces of boost::intrusive_ptr and revise move semantics.
More moving.
Merge branch 'master' into threads

Conflicts:
	value_disambiguation.cpp
Misc.
Have a different function for first and rest of a recursive dive.
Simplify captures.
Remove duplication.