A bunch of logfile changes. Logs are now saved in the experiment
directory so that they can be viewed later after the operation is complete. I've also cleaned up the mechanism for determining when a log file is active (for the web spew) by using another slot in the experiments table, and added some libdb routines to manage that slot. At present just the last (or latest) log can be viewed after the fact, but we can change that later if think its really necessary. At the same time, make it possible for admin types to view the log files for other peoples expierments; spew is setuid, but flips back after opening the file (does usual checks too). I've also incorporated the log changes into the batch daemon, so you can view the last batch log too, although I have not tested that yet!