Provides server-side request and response objects.

This extension provides server-side request and response objects for PHP.

These are *not* HTTP message objects proper. They are more like wrappers for existing global PHP variables and functions.

Four classes and one interface are defined in the global namespace:

- _SapiRequest_, composed of read-only copies of PHP superglobals and some other commonly-used values.

- _SapiUpload_, a value-object style descriptor of each uploaded file.

- _SapiResponse_ and _SapiResponseInterface_, essentially a wrapper around (and buffer for) response-related PHP functions.

- _SapiResponseSender_, for sending a _SapiResponse_.