WSOD when disabling devel_themer module

This appears to be caused by devel_themer, which needs a cache_clear when being disabled. See #213935: Installed an enable all.... Add some code like this when Warn Me disables modules:

      // Clear the theme registry to workaround devel_themer - http://drupal.org/node/213935
      cache_clear_all('theme_registry', 'cache', TRUE);