Extend ArrayObject class

The ArrayObject class is only rarely used at the moment due to a lack for almost all array_* functions beside the sort functions. Currently implemented by ArrayObject: https://www.php.net/manual/en/class.arrayobject.php Missing methods that would be most useful: array_​chunk array_​column array_​diff_​assoc array_​diff_​key array_​diff_​uassoc array_​diff_​ukey array_​diff array_​filter array_​flip array_​intersect_​assoc array_​intersect_​key array_​intersect_​uassoc array_​intersect_​ukey array_​intersect array_​key_​first array_​key_​last array_​keys array_​map array_​merge array_​pop array_​push array_​rand array_​reduce array_​replace_​recursive array_​replace array_​reverse array_​search array_​shift array_​slice array_​splice array_​unique array_​unshift array_​values shuffle Furthermore, the already existing sort functions return VOID, which isn't best for an object. Instead, returning the ArrayObject itself to support a fluid interface would be much better, i.e.: $ao = new \ArrayObject([null, 'a' => 2, 'b' => 1]); $ao->filter()->sort()->flip(); This change wouldn't break any existing code already using the ArrayObject. It should be possible to extend from ArrayObject too and have access to the internal array. Therefore, a new method would be required: protected getArrayRef() : array The method is similar to the existing getArrayCopy() method but returns a reference to the internal array instead of a copy. Thus, classes extending ArrayObject will be able to implement additional methods efficiently without the need to create copies of the internal array first.