reimplemented iter

[dorian3343]

Finally finished iter, which gives us new capabilities when it comes to using lists. A nice example of using iter looks like this,

Print each character on a new line in Neva using Iter

component Main(start any) (stop any) {
    nodes {print Println<string>,iter Iter<string>,unw Unwrap<string>,del Del,split Split}
    net {
        :start -> [
                    ($s -> split:data),
                    ('' -> split:delim)
                ]
        split:res -> iter-> unw:data
        unw:some -> print -> del
        unw:none -> :stop
    }
}