Use object apply count in var_dump / print_r

Use object apply count in var_dump / print_r

Instead of using the array apply count on the debug_info array, use
the object apply count for recursion detection when dumping. This
handles recursion in a more generic way and does not require each
debug_info handler to deal with this.

This allows returning a temporary debug_info array, instead of
having to store it in the object (thus delaying destruction of the
values).

Switch SPL debug_info handlers to use a temporary array.