ScenePlug : Make set() and setHash() friendlier to the hash cache.
ScenePlug : Make set() and setHash() friendlier to the hash cache.

By removing context variables which change frequently but which we know are not allowed to affect sets, we reduce the number of hash cache entries, use less memory, and get more hash cache hits. This reduced scene traversal time for one pathological production case by 30%.

andrewkaufman/gaffer,boberfly/gaffer,boberfly/gaffer,johnhaddon/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,chippey/gaffer,chippey/gaffer,ImageEngine/gaffer,ImageEngine/gaffer,andrewkaufman/gaffer,hradec/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,hradec/gaffer,hradec/gaffer,hradec/gaffer,hradec/gaffer,andrewkaufman/gaffer,ivanimanishi/gaffer,lucienfostier/gaffer,johnhaddon/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,boberfly/gaffer,chippey/gaffer,appleseedhq/gaffer,ivanimanishi/gaffer,boberfly/gaffer,ImageEngine/gaffer,chippey/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,ivanimanishi/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,ivanimanishi/gaffer