doc-src/Intro/list.thy

Replaced ordermap_z_lepoll by ordermap_z_lt, which is
stronger and has a simpler proof. Modified proof of ordermap_csquare_le
accordingly.

List = FOL +
types 	list 1
arities list	:: (term)term
consts	Nil	:: "'a list"
   	Cons	:: "['a, 'a list] => 'a list" 
end