[CCC DEV] Suggestion for Plumbing debounce process

[Steve Pretty]

The current version of debounce is coded:

in ? x
black hole messages on CHAN in for 50ms
out ! x

I would suggest a better solution is:

in ? x
out ! x
black hole message on CHAN in for 50ms

This is just a one line change. The result is exactly the same, except 
it removes the unnecessary 50ms delay on passing on the news about the 
message received on in.  This approach is more concurrent.

I have made this change on my copy of plumbing, and all works well.


Steve