TCP changes I think

From what I can tell, Sepherosa Ziehau’s made some changes where you can control TCP timeout and keepalive timing on a per-tcpcb basis, or at least that’s what I gleaned from the docs.  He’s been doing a lot of work lately, but it’s hard to link to because so much of it is at a basic level that makes it difficult to summarize in terms of how the features affect the user.