* eval.c (unmemoize_quote): New static function.

	* eval.c (unmemoize_quote): New static function.

	(scm_m_quote, scm_m_atslot_ref, SCM_CEVAL): Changed the byte code
	representation of 'quote' and '@slot-ref' to an improper list.
	This reduces execution time, the number of cells used to hold the
	memoized code, and thus also reduces garbage collection time.

	(scm_unmemocopy): Use unmemoize_quote for quote expressions.

	(SCM_CEVAL): Changed macro handling to also work with macros that
	return improper lists.  Added an assertion, that the code returned
	by a macro transformer will not lead to cycles in the memoized
	code.