improve error message
started allowing other arg directives, :thread
pass arg-directives to write-assignments.
but dont use them yet.
begin analyzing arg directives
threading over args is working with some preliminary tests.
	modified:   defmfun1/defmfun1-max.lisp
	modified:   defmfun1/defmfun1.lisp
put threading in several functions
more threading.
add comments
 o partially implement arg directive formatting (eg :thread)
 o wrap printed option list
text formatting of maxdoc prints information on :thread
 arg-directive.
improve printing docs for :thread
update latex, pdf