[PATCH] Handle case where an AI sends an invalid message and then crashes

If an AI sent a bad move and then crashed, a SIGPIPE would be reported
rather than the AI's bad move.

NOTE: There is an issue with Program::Running, because the segfaulted AI
still returns 'true', which leads to confusion in handling SIGPIPE.

Should probably handle segfaulting AIs better.
Then again, people should probably not make segfaulting AIs.

[SZM]