Changes with nginx 0.8.50 02 Sep 2010

*) Feature: the "secure_link", "secure_link_md5", and
"secure_link_expires" directives of the ngx_http_secure_link_module.

*) Feature: the -q switch.
Thanks to Gena Makhomed.

*) Bugfix: worker processes may got caught in an endless loop during
reconfiguration, if a caching was used; the bug had appeared in
0.8.48.

*) Bugfix: in the "gzip_disable" directive.
Thanks to Derrick Petzold.

*) Bugfix: nginx/Windows could not send stop, quit, reopen, and reload
signals to a process run in other session.