Added several new features and fixes.

* New URL mechanism - No longer using the Append the desired URL after miniProxy.php (for example, http://127.0.0.1/miniProxy.php/http://google.com). This removes the need to use an arbitrary query parameter for the desired URL (formerly "___mp_url") and also removes several hacks that were needed to make that mechanism work.
* Basic AJAX support, but only for browsers that use XMLHttpRequest.
* miniProxy now attempts to guess and normalize page encoding.
* All responses from miniProxy are now gzipped.
* miniProxy now correctly proxies as many original response headers as possible (formerly only proxied the "Content-Type" header.)