Deadwood snapshot update: DNS-over-TCP now works

Mr. Max pointed out to me that he couldn't get DNS-over-TCP to work with Deadwood. Looking at the code, I realized that the code would not flush TCP buffers until another TCP connection was made; I have changed the code to flush TCP buffers 20 times a second.

In addition, I have added a SQA regression that tests real-world DNS-over-TCP so that I can ensure DNS-over-TCP doesn't break (I swear DNS-over-TCP worked when I tested it earlier this year after adding buffers).

Finally, I have added a patch that fixes DNS-over-TCP and have verified this patch patches against Deadwood 2.1.01 and Deadwood 2.2.01. I will soon (probably tomorrow) make Deadwood 2.2.02 and 2.1.02 releases with no changes except this patch applied.

For people that want DNS-over-TCP working today, the code can be seen at maradns.org/deadwood/snap