This set of patches separates the representation of the cxr family

	This set of patches separates the representation of the cxr family
	of functions (car, cdr etc.) from the dsubr family of functions
	(i. e. functions that take a double precision floating point
	argument).  Further, the algorithm for handling the cxr function
	is improved.

	* eval.c (SCM_CEVAL, SCM_APPLY, scm_trampoline_1), numbers.c
	(scm_asinh, scm_acosh, scm_atanh, scm_truncate, scm_round, floor,
	ceil, sqrt, fabs, exp, log, sin, cos, tan, asin, acos, atan, sinh,
	cosh, tanh), objects.c (scm_class_of), procprop.c
	(scm_i_procedure_arity), ramap.c (scm_array_map_x), tags.h
	(scm_tc7_dsubr, scm_tcs_subrs): Introduce scm_tc7_dsubr as new
	typecode for the dsubr family of functions.

	* ramap.c (ramap_cxr, ramap_dsubr): Renamed ramap_cxr to
	ramap_dsubr.

	* eval.c (SCM_CEVAL, SCM_APPLY, call_cxr_1), pairs.c
	(scm_init_pairs): Make use of the (now usable) second cell element
	of a scm_tc7_cxr function to implement the cxr family of functions
	more efficiently.