Deprecate C exports of GOOPS classes.

Deprecate C exports of GOOPS classes.

* libguile/deprecated.h:
  (scm_class_boolean, scm_class_char, scm_class_pair)
  (scm_class_procedure, scm_class_string, scm_class_symbol)
  (scm_class_primitive_generic, scm_class_vector, scm_class_null)
  (scm_class_real, scm_class_complex, scm_class_integer)
  (scm_class_fraction, scm_class_unknown, scm_class_top)
  (scm_class_object, scm_class_class, scm_class_applicable)
  (scm_class_applicable_struct, scm_class_applicable_struct_with_setter)
  (scm_class_generic, scm_class_generic_with_setter, scm_class_accessor)
  (scm_class_extended_generic, scm_class_extended_generic_with_setter)
  (scm_class_extended_accessor, scm_class_method)
  (scm_class_accessor_method, scm_class_procedure_class)
  (scm_class_applicable_struct_class, scm_class_number, scm_class_list)
  (scm_class_keyword, scm_class_port, scm_class_input_output_port)
  (scm_class_input_port, scm_class_output_port, scm_class_foreign_slot)
  (scm_class_self, scm_class_protected, scm_class_hidden)
  (scm_class_opaque, scm_class_read_only, scm_class_protected_hidden)
  (scm_class_protected_opaque, scm_class_protected_read_only)
  (scm_class_scm, scm_class_int, scm_class_float)
  (scm_class_double, scm_port_class, scm_smob_class): Deprecate.

* libguile/deprecated.c:
* libguile/goops.c:
* libguile/goops.h: Adapt to deprecation.

* libguile/goops.h
* libguile/goops.c (scm_is_generic, scm_is_method): New interfaces.
  (SCM_GENERICP, SCM_METHODP): Change to use new interfaces.

* libguile/ports.c (scm_make_port_type):
* libguile/smob.c (scm_make_smob_type, scm_set_smob_apply): Use internal
  names for the port and smob class arrays.