procedures-with-setters implemented in terms of structs

procedures-with-setters implemented in terms of structs

* libguile/tags.h (scm_tc7_pws): No more.

* libguile/procs.c (scm_procedure_with_setter_p)
  (scm_make_procedure_with_setter, scm_procedure, scm_setter): Implement
  procedures-with-setters in terms of applicable structs with setters.

* libguile/procs.h: Remove a big, outdated comment, and the deprecated
  macros.

* libguile/deprecated.h (SCM_PROCEDURE_WITH_SETTER_P, SCM_PROCEDURE)
  (SCM_SETTER): Deprecate these. SCM_PROCEDURE and SCM_SETTER are bad
  names.

* libguile/evalext.c (scm_self_evaluating_p):
* libguile/gc.c (scm_i_tag_name):
* libguile/goops.c: (scm_class_of):
* libguile/print.c (iprin1):
* libguile/procprop.c (scm_i_procedure_arity):
* libguile/procs.c (scm_procedure_p):
* libguile/debug.c (scm_procedure_source): Remove a tc7_pws case.

* libguile/goops.h:
* libguile/goops.c (scm_class_procedure_with_setter): Remove this class;
  it is subsumed by applicable_struct_with_setter.

* libguile/struct.h: Update a comment.

* libguile/vm-i-system.c (call, goto/args, mv-call): Remove PWS cases.