Settings repository clean-up of outdated settings

My primary interest in this is for PhpStorm at work, but it applies to the other IDEs that can use the settings repository feature too. Is there a way to clean up the settings repository to get rid of settings that've moved or been reorganized? For instance, in a saved code styles XML file I find PHP code style settings under a <PHPCodeStyleSettings> element and also under a <codeStyleSettings language="PHP"> element. It'd be nice to have some way of removing settings that aren't used anymore, even if it's by a crude method like "export settings excluding any not currently used by this IDE" and then reimporting them into a clean installation of the IDE.