3 changes. First merge some of Mike's changes from the capture source
code I found in /foo/x/mike/src/capture/capture.c. Second, add a -r option to open up a second log file called the "run" file, which is intended to be used for the experiment session log. This log is restarted with a SIGUSR1. Third, add SIGUSR2 handler to close the pty side of the capture, which has the nice side effect of causing tip to exit gracefully.