Merge PR 109 - Add create_sid to session_set_save_handler and SessionHandler

Allows user session handlers to create session IDs by adding an optional
7th argument to session_set_save_handler() and a create_sid() method
to SessionHandler.

diff --cc ext/session/mod_user.c
Simple merge

diff --cc ext/session/mod_user.h
Simple merge

diff --cc ext/session/mod_user_class.c
Simple merge

diff --cc ext/session/php_session.h
Simple merge

diff --cc ext/session/session.c
Simple merge