/**
 * @returns {any} Randomly picked item, null when length=0
 */
Array.prototype.random = function() {
	if (!this.length) { return null; }
	return this[Math.floor(ROT.RNG.getUniform() * this.length)];
}

/**
 * @returns {array} New array with randomized items
 * FIXME destroys this!
 */
Array.prototype.randomize = function() {
	var result = [];
	while (this.length) {
		var index = this.indexOf(this.random());
		result.push(this.splice(index, 1)[0]);
	}
	return result;
}