// Return an object who's members match a reference array of keys
// reference=["b","c","f","r"];
// obj={"a":1, "b":2, "c":3, "d":4, "r":18};
// _.filterObj(obj, reference)
// => { b : 2, c : 3, r : 18}
_.mixin( {
	filterObj : function( obj, reference ) {
		if ( reference && typeof reference == 'object' ) { reference=_.keys( reference ); }
		var intersect = _.intersect(reference, _.keys(obj)), retObj= {};
		_.map( intersect, function( el) { retObj[el]=obj[el];})
		return retObj;
	}
});