Fri Oct 11 13:37:14 2002  George Lebl <jirka@5z.com>

	* src/calc.c, src/eval.c, src/parse.y, src/lexer.l,
	  src/parseutils.[ch], src/structs.h, compil.c: Add vararg functions

	* lib/linear_algebra/linear_algebra.gel: Add vector of matrices
	  direct sum function, and make the direct sum use varargs.
	  Also change is_invertible to IsInvertible and add
	  IsInvertibleField.  Also fix Jordan block function for n==1
	  and add some argument checking

	* lib/combinatorics/recursive_sequences.gel: use IsInvertible name