Try without identifying current user

Small change that warns the user if the current user cannot be identified rather than aborting.  This came in handy when I put dropbear on a dlink that did not have a true user environment.  Falling back on the "-l" option and user@ options works just fine as a client.  The only implication I found is that the -J option will fail ungracefully without a known own_user.

- Add release script
- Simplify print_version

-h should exit with success
Update manpages

if (connecting || ptys || x11) tos = LOWDELAY;
else if (tcp_forwards) tos = 0;
else tos = BULK;

TCP forwards could be either lowdelay or bulk, hence the default priority.

connection backlog, avoid check_close() for channels that haven't had IO

auth requests). Regresssion in ff597bf2cfb0

EAGAIN but always saves a select() - needs testing with bandwidth-limited
and CPU-limited situations.

system clock changes

While at it, fix a few indentations and typo.

be more precise about maximum channel sizes