throughput and tx rate in marginal signal conditions

[mlamb at roinet.com]

We're still testing the patch, but performance under sketchy conditions
seems vastly improved.

Last night we had some problems with connections *never* throttling back,
but after we made Jouni's change (consecutive drops >= threshold rather
than just >), that seems to be repaired.  I suspect that having an
effective threshold of 3 drops was a little too aggressive; 2 seems to be
much better.

Martin Lamb
ROI Computer Services, Inc.