Payment channel API, client suggests channel time window

Lets the client request the duration of a payment channel. Servers can accept or deny the request.
The client's version message now takes an optional time window parameter. It defaults to 24h - 1 minute.
The server will by default allow channels to have 4 h to 1 week time window. There is a hard limit of 2 h on the server minimum time window, causing a IllegalArgumentsException, since it takes about 2 h to close the channel.
Correct, there is a trade off. We all want this numbers to be in a logical order, even if it does not matter. And just as you point out, no one is probably using this in prod now, so it is possible to make it as neat a possible. I have no firm beliefs here.