Added array methods from MooTools

I've added the following methods to the array shell:

clean


    invoke: function(methodName){


    associate: function(keys){


    contains: function(item, from){


    append: function(items){


    last: function(){


    random: function(){


    include: function(item){


    combine: function(items){
        for (var i = 0, l = items.length; i < l; i++) array.include(this, items[i])
        return this
    },

    erase: function(item){

    empty: function(){

    pick
    }