* procs.c, procs.h (scm_subr_entry): New type: Stores data

* procs.c, procs.h (scm_subr_entry): New type: Stores data
associated with subrs.
(SCM_SUBRNUM, SCM_SUBR_ENTRY, SCM_SUBR_GENERIC, SCM_SUBR_PROPS,
SCM_SUBR_DOC): New macros.
(scm_subr_table): New variable.
(scm_mark_subr_table): New function.

* init.c (scm_boot_guile_1): Call scm_init_subr_table.

* gc.c (scm_gc_mark): Don't mark subr names here.
(scm_igc): Call scm_mark_subr_table.

* snarf.h (SCM_GPROC, SCM_GPROC1): New macros.

* procs.c, procs.h (scm_subr_p): New function (used internally).

* gsubr.c, gsubr.h (scm_make_gsubr_with_generic): New function.

* objects.c, objects.h (scm_primitive_generic): New class.

* objects.h (SCM_CMETHOD_CODE, SCM_CMETHOD_ENV): New macros.

* print.c (scm_iprin1): Print primitive-generics.

* __scm.h (SCM_WTA_DISPATCH_1, SCM_GASSERT1,
SCM_WTA_DISPATCH_2, SCM_GASSERT2): New macros.

* eval.c (SCM_CEVAL, SCM_APPLY): Replace scm_wta -->
SCM_WTA_DISPATCH_1 for scm_cxr's (unary floating point
primitives).  NOTE: This means that it is now *required* to use
SCM_GPROC1 when creating float scm_cxr's (float scm_cxr's is an
obscured representation that will be removed in the future anyway,
so backward compatibility is no problem here).

* numbers.c: Converted most numeric primitives (all but bit
comparison operations and bit operations) to dispatch on generic
if args don't match.

* eval.c, eval.h (scm_eval_body): New function.

* objects.c (scm_call_generic_0, scm_call_generic_1,
scm_call_generic_2, scm_call_generic_3, scm_apply_generic): New
functions.

* eval.c (SCM_CEVAL): Apply the cmethod directly after having
called scm_memoize_method instead of doing a second lookup.

* objects.h (scm_memoize_method): Now returns the memoized cmethod.

* procs.c (scm_make_subr_opt): Use scm_sysintern0 instead of
scm_sysintern so that the binding connected with the subr name
isn't cleared when we give set = 0.