* print.c (scm_iprin1): Handle fractions.

* print.c (scm_iprin1): Handle fractions.

* objects.h (scm_class_fraction): New.
* objects.c (scm_class_fraction): New.
(scm_class_of): Handle fractions.

* hash.c (scm_hasher): Handle fractions.

* numbers.c: New code for handling fraction all over the place.
(scm_odd_p, scm_even_p): Handle inexact integers.
(scm_rational_p): New function, same as scm_real_p.
(scm_round_number, scm_truncate_number, scm_ceiling, scm_floor):
New exact functions that replace the inexact 'dsubr'
implementations.
(scm_numerator, scm_denominator): New.

* numbers.h (SCM_NUMP): Recognize fractions.
(SCM_FRACTIONP, SCM_SLOPPY_FRACTIONP, SCM_FRACTION_NUMERATOR,
SCM_FRACTION_DENOMINATOR, SCM_FRACTION_SET_NUMERATOR,
SCM_FRACTION_SET_DENOMINATOR, SCM_FRACTION_REDUCED_BIT,
SCM_FRACTION_REDUCED_SET, SCM_FRACTION_REDUCED_CLEAR,
SCM_FRACTION_REDUCED): New.
(scm_floor, scm_ceiling, scm_truncate_number, scm_round_number):
New prototypes.
(scm_make_ratio, scm_rationalize, scm_numerator, scm_denominator,
scm_rational_p): New prototypes.
(scm_i_dbl2num, scm_i_fraction2double, scm_i_fraction_equalp,
scm_i_print_fraction): New prototypes.

* goops.c (create_standard_classes): Create "<fraction>" class.

* gc-mark.c (scm_gc_mark_dependencies): Handle fractions.

* gc-card.c (scm_i_sweep_card): Include scm_tc16_fraction as a
case in the switch, but do nothing for now.

* eval.c (SCM_CEVAL, SCM_APPLY, call_dsubr_1): Convert fractions
to doubles when calling 'dsubr' functions.

* eq.c (scm_eqv_p, scm_equal_p): Handle fractions.