This work is based on Anthony Hannan's original SystemTracer2. It adds a
RehashingSystemTracer that allows you to manipulate identity hash values
during a trace. See the class comments for SystemTracer2 and
RehashingSystemTracer for more details.

RECOMMENDED: It is recommended that you load the "Large Collections"
package (available on SqueakMap) to get better performance. A trace on
my machine that took 9.7 minutes without large collections took only 2.5
minutes with large collections loaded. Large collections are
recommended, but not required for SystemTracer2 to work.

- Stephen