function copy2( arr ) {
	var out;
	var len;
	var i;

	len = arr.length;
	out = new Array( len );
	for ( i = 0; i < len; i++ ) {
		out[ i ] = arr[ i ];
	}
	return out;
}
Copies an array by preallocating output array memory.

@private
@param {Array} arr - array to copy
@returns {Array} array copy