small cleanup and documentation on pattern matcher

git-svn-id: http://haxe.googlecode.com/svn/trunk@6626 f16182fa-f095-11de-8f43-4547254af6c6
improved error message when iterator is not a Void -> T method (fixed issue #1812)

git-svn-id: http://haxe.googlecode.com/svn/trunk@6627 f16182fa-f095-11de-8f43-4547254af6c6