- Added additional logging.
- Removed all #ifdef _DEBUG around existing logging statements, allow LogLevel to decide.
- Code now inserts an input header "X-SENDFILE-INVOKED" before making a subrequest, which can cause mod_rewrite to fire a second time.  The header allows a RewriteCond to be used to skip any rules that should not re-apply.
- Replaced code that insert the requested file into buckets with the newer apr_bridge_insert_file command, which properly handles large files.
- Replace code that empties the incoming brigade with apr_brigade_cleanup, which does the same thing but in one command.