Description:
------------
Php should have a friend structure for classes, like c++.
That way some normaly private things can be used by selected other classes and functions.

An alternative would be to do it like Java with inner classes, but personaly I think that while inner classes could be usefull in php, friend classes should also exist like in c++.

Reproduce code:
---------------
<?php
//my suggestion for the syntax
class A {
 static function callB(B $b) {
  $b->privatefunction();
 }
}

class B {
 friend class A;
 friend function C;

 private function privatefunction() {
  echo 'privatefunction!';
 }
}

function C(B $b) {
 $b->privatefunction();
}

$b=new B();
A::callB($b);
C($b);

Expected result:
----------------
Class A and function C should be able to call B::privatefunction.

Actual result:
--------------
Since this functionality doesn't exist the code wont even compile.