Bug 358783

While it is possible to save the "Fade from Black" effect with a custom setting differing from the 75 frames default, saving the sibling "Fade to Black" effect doesn't work correctly. A custom effect made from "Fade to Black" doesn't correctly the duration parameter semantics. In fact, the custom setting does not correctly contain a negative durations/in parameter as it would be necessary but instead the calculated in point for the clip from which the effect was saved.

Reproducible: Always

Steps to Reproduce:
1. Drag clip into timeline.
2. Add "Fade to Black" effect to clip, change duration to 12 frames.
3. Save effect as custom effect.
4. Drag another clip into timeline.
5. Add saved custom effect to second clip.

Actual Results:  
The duration parameter is messed up and basically corresponds with the "in" point of the Fade to Black effect on the clip from which the custom effect was saved.

Expected Results:  
Duration parameter to correctly reflect the value as set on the effect/clip from which the custom effect was saved.