[3603557]: Increase the maximum depth of recursion used when duplicating an
automaton in response to encountering a "wild" RE that hit the previous limit.
Allow the limit (DUPTRAVERSE_MAX_DEPTH) to be set by defining its value in the
Makefile. Problem reported by Jonathan Mills.
[3603804]: Improve example to actually be capable of throwing the trapped errors
merge trunk. Simplify Reference struct of tclPreserve.c.