OCI8拡張ライブラリ

Major changes:
--------------
- The connection handling algorithm was rewritten. That should add 
stability and fix all non-reproducible crashes etc;
- The extension was refactored and divided into several files to 
improve readability and to make it easier to maintain;
- Added support for statement caching;
- Added support for privileged connections using external credentials;
- Added new INI options to manage persistent connections;
- Fixed oci_close() to close connections correctly.

コレなんですが、一番最後の部分はチョー重要！
ようやく昔の呪縛から開放されそうな予感。その他、多くの改良が加えられています。