"clogger_ext" is no longer a separate gem, but merged into the
"clogger" gem itself. The installation should automatically
detect compatible versions of Ruby and only build the C
extension for MRI 1.8/1.9.

Rack::Utils::HeaderHash is now used for $sent_http_* variable
lookups instead of a hand-rolled solution. HeaderHash objects
should be reusable in Rack soon to avoid the penalty of
recreating them repeatedly in middlewares and hopefully
more-widely used as a result.

Underlying logger objects are sync=true for safety reasons.
This has always been the case for the C extension version
when writing to regular files.

Other small changes include more CGI variables and the :ORS
(output record separator) option added (default: "\n").