* lisp/register.el: Use cl-generic

* lisp/register.el: Use cl-generic

(registerv): Make it a "normal"struct.
(registerv-make): Declare obsolete.
(register-val-jump-to, register-val-describe, register-val-insert):
New generic functions.
(jump-to-register, describe-register-1, insert-register): Use them.

* lisp/emacs-lisp/cl-generic.el: Prefill a combination of struct+typeof.
(cl--generic-prefill-dispatchers): Allow a list of specializers.