Adds a flag to set the SSH forwarding port or port range used for
'cdc_stream start-service' and 'cdc_rsync'.
If a single number is passed, e.g. --forward-port 12345, then this
port is used without checking availability of local and remote ports.
If the port is taken, this results in an error when trying to connect.
Note that this restricts the number of connections that stream can
make to one.
If a range is passed, e.g. --forward-port 45000-46000, the tools
search for available ports locally and remotely in that range. This is
more robust, but a bit slower due to the extra overhead.
Optimizes port_manager_win as it was very slow for a large port range.
It's still not optimal, but the time needed to scan 30k ports is
<< 1 seconds now.
Fixes#12
Starts the streaming service if it's not up and running. This required
adding the ability to run a detached process. By default, all child
processes are killed when the parent process exits. Since detached
child processes don't run with a console, they need to create sub-
processes with CREATE_NO_WINDOW since otherwise a new console pops up,
e.g. for every ssh command.
Polls for 20 seconds while the service starts up. For this purpose,
a BackgroundServiceClient is added. This will be reused in a future CL
by a new stop-service command to exit the service.
Also adds --service-port as additional argument to start-service.
