* now we require at least libdrizzle 1.0, which supports official mysql 5.5+ and is much more stable under load. thanks Taylor Weibley for pushing this. We no longer require patching libdrizzle any more.
* fixed a compilation issue on Mac OS X: we should include drizzle.h prior to nginx headers, or we will not get the "bool" type properly installed on Mac OS X.
* fixed the spots that trigger -Wunused-but-set-variable by gcc 4.6.
* fixed the duplicate last chunk issue: we should not set the last_buf flag ourselves in drizzle_output.c because ngx_http_upstream already sends a last buf for us.
* ported over Maxim Dounin's patch for ngx_http_upstream_keepalive connection pool fixes: we should have discarded stale read events for cached tcp connections in the pool.
* implemented the new drizzle_status directive to provide connection pool status monitoring capability.
* fixed a minor bug in the connection pool: we should resume the "name", "sockaddr", and "socklen" fields for the connection from the pool such that we can get more detailed error log messages with the "upstream: drizzle://ip.add.re.ss:port" bit.
* implemented the $drizzle_thread_id variable which is automatically set when mysql/drizzle times out.
* now we use the 2-clause bsd license.
* report an error message when upstream name not found for drizzle_pass.
* now we implemented the charset option for the "drizzle_server" diredctive which causes ngx_drizzle send "set names xxx" automatcially for every connection to that drizzle server.