* Prevent E_STRICT error when '$wgDebugDumpSql = true', and a path has been defined...

* Prevent E_STRICT error when '$wgDebugDumpSql = true', and a path has been defined for $wgDebugLogFile,
  but $wgDebugLogFile does not exist yet: "filesize(): stat failed for sql-log.txt in includes/GlobalFunctions.php on line 219"
* Removing unused global $IP.
* Indentation of an if/else block.
* Trivial comment typo.
* Prevent PHP Fatal error: "Call to a member function getText() on a non-object in includes/SpecialListusers.php on line 46",
  when opening a URL such as http://192.168.0.64/wiki/index.php/Special:Listusers?username=%22%27%3E
  (i.e. when "Display users starting at:" username supplied in Special:Listusers is not a valid MediaWiki title).
* Fix HTML validation of protection form (i.e. when "action=protect").