Minor bugfix: Fixed broken debug argument.

Minor bugfix: Fixed broken debug argument.

Internal changes: Only create a DebugTimer when actually called for;
moved debug message out of page content and into deferred page error
notification via trigger_error. Memory management: Only include_once
lib/PageList when absolutely necessary (at this time, this will
probably only benefit the PluginManager as an incremental speedup &
slightly reduced memory).

git-svn-id: svn://svn.code.sf.net/p/phpwiki/code/trunk@2924 96ab9672-09ca-45d6-a79d-3d69d39ca109