Fix invalid memory read
Fix crashes under Valgrind

* Fix crashes under valgrind when Zend MM is used;
* Double the number of preallocated frames (based on the longest
  execution path)
* More checks for the debug mode
Optimize/annotate kernel/object.h
Bug fix for PHP 5.3
Merge pull request #2003 from sjinks/obj-opt

Optimize/annotate kernel/object.h