Improve funcoid rendering code.

2013-06-18  Didier Verna  <didier@didierverna.net>

	* src/doc/symbol.lisp (render-funcoid): Only render the body, not
	the toplevel @def forms.
	(document (function-definition)):
	(document (macro-definition)):
	(document (compiler-macro-definition)):
	(document (accessor-definition)):
	(document (generic-definition)):
	(document (generic-accessor-definition)): Update accordingly.
Support macro and setf expander definition merging.

2013-06-19  Didier Verna  <didier@didierverna.net>

	* src/util/texi.lisp (@defmac): Rename to @defmacro. Implement in
	terms of Texinfo command @deffn instead of @defmac.
	(@defsetfx): New macro.
	* src/doc/symbol.lisp (document (macro-definition)): Update
	accordingly. Merge rendering with the setf expander when possible.
Factor out @def*x rendering.

2013-06-19  Didier Verna  <didier@didierverna.net>

	* src/util/texi.lisp (@deffnx): New function.
	(@defsetfx):
	(@defgenericx):
	(@defmethodx): Use it.
Code cleanup.

2013-06-19  Didier Verna  <didier@didierverna.net>

	* src/doc/symbol.lisp (document (accessor-definition)):
	(render-method-combination):
	(document (generic-accessor-definition)): Bind frequently used
	slots to local variables.