Introduce scm_debug_mode_p as a replacement for scm_debug_mode and

	Introduce scm_debug_mode_p as a replacement for scm_debug_mode and
	SCM_DEBUGGINGP:

	* debug.h (scm_debug_mode_p, scm_debug_mode, SCM_DEBUGGINGP),
	eval.c (scm_debug_mode_p): Deprecated scm_debug_mode and
	SCM_DEBUGGINGP.  Provided scm_debug_mode_p instead, to have one
	single interface that also matches the naming conventions.
	Probably scm_debug_mode_p should be part of the private interface
	anyway.

	* debug.h (scm_debug_mode_p), backtrace.c (display_error_body),
	eval.c (SCM_APPLY, scm_trampoline_0, scm_trampoline_1,
	scm_trampoline_2): Change uses of scm_debug_mode or SCM_DEBUGGINGP
	to scm_debug_mode_p.

	Deprecate direct access to scm_ceval, scm_deval and scm_ceval_ptr:

	* eval.h (scm_ceval, scm_deval, scm_ceval_ptr), debug.h
	(scm_ceval_ptr): Deprecated.  Moved declaration of scm_ceval_ptr
	from debug.h to eval.h.

	* debug.h (SCM_RESET_DEBUG_MODE): Don't access scm_ceval_ptr any
	more, just leave it with setting scm_debug_mode_p, which is
	equivalent for practical purposes.

	* deprecated.h (SCM_XEVAL, SCM_XEVALCAR): Call scm_i_eval_x
	instead of *scm_ceval_ptr.  Leave all evaluating to scm_i_eval_x.

	* gdbint.c (gdb_eval): Call scm_i_eval_x instead of scm_ceval.

	* eval.c (ceval, deval, scm_ceval, scm_deval): Made scm_ceval
	static and renamed it to ceval throughout.  Provide a new exported
	but deprecated function scm_ceval as a wrapper for backwards
	compatibility.  The same is done for the deval/scm_deval pair of
	functions.

	* eval.c (CEVAL, SCM_CEVAL): Renamed SCM_CEVAL to CEVAL
	throughout.  Defined CEVAL to ceval or deval, based on compilation
	phase.

	* eval.c (SCM_XEVAL, SCM_XEVALCAR): Dispatch on scm_debug_mode_p
	to ceval and deval instead of calling *scm_ceval_ptr.

	* eval.c (dispatching_eval): New deprecated static function.

	* eval.c (scm_ceval_ptr): Initialized to dispatching_eval in order
	to emulate its old behaviour as closely as possible.

	Change the evaluator such that only expressions for which pair? is
	true are passed to CEVAL, and such that all other expressions are
	evaluated outside of CEVAL:

	* eval.c (EVAL): New, provided in analogy to EVALCAR.  Evaluate an
	expression that is assumed to be memoized already.  All but
	expressions of the form '(<form> <form> ...)' are evaluated inline
	without calling an evaluator.

	* eval.c (SCM_XEVAL, SCM_XEVALCAR, EVALCAR): Evaluate all but
	expressions of the form '(<form> <form> ...)' inline without
	calling an evaluator.

	* eval.c (scm_i_eval_x, scm_i_eval, scm_ceval, scm_deval): Handle
	the special case of unmemoized symbols passed on the top level.

	* eval.c (CEVAL): Change calls to CEVAL to EVAL, except where it
	is known that the expression passed to CEVAL is of the form
	'(<form> <form> ...)'.  Remove handling of the tc7-objects, since
	now it is known that the input expression of CEVAL is a pair.