"Disable filter cache" actually *enables* caching

The filter caching logic appears to be backwards at some level; when the "Disable filter cache" box in "Freelinking settings" is NOT checked, caching is disabled for any input format that uses freelinking. However, if you check the box, caching *will* be enabled for that format.

From code inspection it's not 100% clear whether this is due to simply not needing the '!' in hook_filter's 'no cache' op, or to something more subtle at another level of the freelinking configuration system.