Rework of the batch experiment code. Unified it with the immediate
experiment code. No longer uses another table. Rather, the experiment record contains a couple of extra fields for the batch system. Also combined some of the backend code (no longer a killbatch script). Also added scriptable experiments; the batchexp program in the bin directory can start an experiment from the command line, and in fact is used from the web page for both batch experiments and immediate experiments (-i option). All of the DB code that was in the web interfaces was moved to batchexp.