M2 should generate log files of all user input so bug reporting can be more
accurate.  There should be a command line option to turn it off, and it should
automatically turn off if stdin is not a tty device.

Older files should be deleted automatically -- keep just 25?  Make that an
option?

Flush the output buffer after each input expression, in case Macaulay 2 crashes.

Start the file with info about the M2 version.

There could be a File corresponding to the open log file, so debugging code
can send stuff there.

It could be implemented by means of a new hook: "BeforeEval", which could even
change the input string from the user.

It could be part of a Logging package, with configuration settings, etc.
