Better handling of reconnects

[tionis]

I discovered a potential problem when using sish/tuns.sh with tunmgr:

If the internet connection has a glitch and the ssh connection is lost, tunmgr tries to reconnect with the same parameters but gets assigned a new domain due to the old one still being blocked by the not yet timed out old connection
Perhaps sish could get support for e.g. some force parameter in the command to kill the old connection when a new one is established?