Make config change detection smarter.

If a runtime change is made to a static configuration item, it will cause warnings later when the the config is loaded. That is appropriate if the static configuration has been changed, after the runtime was made. But inappropriate and scary if the static configuration has not been changed.

When the runtime change is saved, information that allows the loading mechanism to detect whether the static configuration has been modified after the runtime change, should also be saved. That could be e.g. a hash of the settings of the configuration item.