PHP5 improvements

[Zurab Davitiani]

Just want to note few improvements I saw, beyond obvious, while porting my
packages to PHP5 (in case anyone is interested):

- garbage collection seems to have much improved compared to PHP4; and I
don't mean for the session files and data, but for objects and variables
while the script is running;

- the undocumented [yet] clone() function to create copies of objects;

- much better implementation of overloading;

- flexible interfaces; even though personally I would have preferred
multiple inheritance, the interfaces may be good enough to get by - one
interface can extend another, a class can implement multiple interfaces and
inherit from another class simultaneously.

One thing I do not like is the way the "protected" encapsulation works
because there's no notion of packages in PHP (like in Java). This forces
some of the methods to be "public" when it's not necessary. Overall, so far
so good!