* fixed http_cache_last_modified(): if parameter was omitted, would have always sent...

* fixed http_cache_last_modified(): if parameter was omitted, would have always sent 304 Not Modified
* we do not need to suggest closing the connection in http_cache_etag() as we'll end the ob_buffer
* made http_redirect() really RFC compliant by writing out "Redirecting to <link>URI</link>."
* separate params argument in http_redirect()
* remember sent etag and last-modified as globals
* new HTTP_SERVER_VARS define
* only try to match the etag in http_ob_etag_handler() if we have not been stopped so far
* ignore spaces in range request of IE
* free zranges where they've been initialized
* caching handling in http_send()
* update package.xml