[Discuss-gnuradio] scheduler tweaks

[Eric Blossom]

FYI,

I just checked in some scheduler tweaks that I believe fix the problem
where folks saw the output through the pipeline running slowly.  As I
recall these were cases where depending on what blocks were hooked up,
you'd get different throughput.  Chuck, this may have been the problem
you were seeing with your PSK code.

Anyhow, the changes fix the behavior shown by my test case ;)

Summary of change: the scheduler now ensures that it moves as much
data through each block as it can on each iteration.

Eric