OPCODE CACHE
============
  + scripts should not be compiled and stored more than once
  + memory usage information for windows version
  + shared memory overflow detection
  + crash detection
  - class_entry storing routine should not store parent class methods.
    Now they are optimized and stored twitch

OPTIMIZER
=========
  - eliminate unnecessary INIT_FCALL_BY_NAME
  - eliminate unnecessary references to global variables

ENCODER & LOADER
================