new subproject: statuswin.exe

For displaying a message on the logon screen.
statuswin: introduce two static controls to hold the messages
statuswin: order up a custom font to improve appearance
statuswin: create a UDP socket to listen for datagrams
statuswin: show default pointer when mouse is over window
add to project: maintenance-script-service
maintenance-status: first attempt at launching status window (failed)

Still launching in "session 0", where all the services live.
statuswin: teach Maintenance script about starting processes in other session
statuswin: use launch_in_session to launch statuswin.exe
statuswin: create a status.exe binary to send messages
statuswin: distinguish between primary and secondary messages

also support -hide to hide the window