#114 media rate slider does not work

[Jonathan Kilgour]

In most cases and on most platforms the rate slider on the NITE Clock inteface actually has no effect on the replay speed of the media. Worse than that, it's only on the Mac platform where FMJ is used that an explicit error message is printed (only on teh console) when you try to set the rate: FMJ does not support rate changes. Investigate the problem to see if it can be solved and at the very least grey out the slider and/or give errors if rate changes will have no effect.