main_gui: implement /port, which net.cpp already documented (#28)

net.cpp has described nListenPort as "tunable via /port" since it was written:

    unsigned short nListenPort = DEFAULT_PORT; // local P2P port (tunable via /port)

Nothing ever parsed the option. The port was fixed at 8433, so a second node
could not start on a machine already running one -- StartNode fails the bind and
the node comes up with no networking at all. That makes local multi-node testing
impossible, which is how this was found: a two-node test could not be run.

Sets addrLocalHost.port alongside nListenPort, or the node announces a port it
never bound. An out-of-range value is rejected with a message and the default
kept, rather than silently wrapping through the unsigned short cast.

0 files changed, 0 insertions, 0 deletions