Code cleanup.

2013-06-20  Didier Verna  <didier@didierverna.net>

	* src/doc/symbol.lisp (render-funcoid): Encapsulate the Texinfo
	macro to use, specified by a new KIND first argument.
	(document (macro-definition)):
	(document (compiler-macro-definition)):
	(document (writer-definition)):
	(document (accessor-definition)):
	(document (generic-definition)):
	(document (generic-accessor-definition)):
	(document (setf-expander-definition)): Update accordingly.
Fix UPDATE-EXPANDER slot location.
Put it only in structures where it makes sense; not in all funcoids.

2013-06-20  Didier Verna  <didier@didierverna.net>

	* src/item/symbol.lisp (funcoid-definition): Remove the
	UPDATE-EXPANDER slot.
	(macro-definition):
	(function-definition):
	(generic-definition): Add it here instead.
	(finalize-definitions): Update accordingly.
	* src/doc/symbol.lisp (render-funcoid): Remove handling of deleted
	slot.
	(document (macro-definition)):
	(document (function-definition)):
	(document (accessor-definition)):
	(document (generic-definition)):
	(document (generic-accessor)): Handle it here instead.