Fri Jun 24 17:21:22 2005  George Lebl <jirka@5z.com>

	* src/symbolic.c, src/eval.c, src/geniustests.txt: Some more
	  simplification special casing, doing several tan derivatives is
	  now much faster and results in shorter answers, yay.  Also run
	  the evalnode hook so that we can interrupt a symbolic derivation
	  which is taking too long.