added -D no-unused-var-warnings

git-svn-id: http://haxe.googlecode.com/svn/trunk@5968 f16182fa-f095-11de-8f43-4547254af6c6
do not warn about unused capture-vars if they start with _

git-svn-id: http://haxe.googlecode.com/svn/trunk@5969 f16182fa-f095-11de-8f43-4547254af6c6