sets: adding union! and intersection.
sets: adding diff!.
vocabs.parser: use hash-sets in search-vocab-names.
classes: store implementors in hash-sets.
compiler: use hash-sets to track visited sets.
compiler: fix stack effects to indicate visited is same object.
compiler.tree.propagation.info: inline <value-info>.
compiler.cfg.ssa.construction: more use of hash-sets.
compiler.cfg.write-barrier: more use of hash-sets.
compiler.tree.recursive: more use of hash-sets.
compiler.cfg.loop-detection: more use of hash-sets.
misc/fuel: try and fix autodoc bug report.
tools.profiler.sampling: more use of hash-sets.
classes.tuple: require boa words to have tuple-class arguments.
parser: fix tests for hash-set change.