Fix calculation of send_timeout based on hop_counts

-Updated to allow for a hop_count of 0.  The comments in the file noted that a hop count of zero should exist, but never made allowances for it.

-Fixed the calculation used to determine the hop count.  Looks like a logical error, send_attempts was being added to default_hop_count and then decreased by one.  Not sure the logic here.  Default_hop_count is equal to send_attempts up to 3 attempts, so unless the device lacks a default_hop_count, which I believe is only the PLM, there is no need to look to send attempts.  Moreover, adding send_attempts and hop_count was resulting in an anomolous situation in which the timeout could be double what it should be.

-Shifted hop_count timeout allocations by one.  This matches what is in the comment section, but for some reason was not implemented.