Requests for 4.16 - 4.17

Something really small:

-Enhance the UPROPERTY ‘EditCondition’ specifier to allow more than just boolean variable conditions. For a catch-all solution without too much hassle, allow to specify the name of a UFUNCTION returning bool and call it at runtime.
-Similarly, add a ‘VisibleCondition’ specifier! Would really clean up some of my UIs.