transition error when you click too fast after creating it. Instead of
looking at experiment state, use the logile slot of the experiments
table, and make sure its cleared/set properly in start/swap experiment
scripts.

Also added a spew option to the swap page so you can watch experiments
swap in/out.

experiment log file to the user as it gets generated. The web page
does not redraw, it just never exits until the backend sees that the
experiement transition is done, and then it exists, which terminates
the script. I added a DB field to hold the logfile name and some
routines in libdb, with the idea that this might be more generally
useful at some point. Next time you create an experiment, look for the
last sentence, and click on "realtime".