Hash = function() {
	this._map = {};
	this._keys = [];
	this._vals = [];
	this.reset();
}
@constructor
	@example
	var _index = new Hash();
	_index.set("a", "apple");
	_index.set("b", "blue");
	_index.set("c", "coffee");

	for (var p = _index.first(); p; p = _index.next()) {
		print(p.key+" is for "+p.value);
	}