We now maintain a virtual root loger, on which you can set the log
level. When any logger logs, it finds the effective log level by going
up the parent chain, and finding a meaningful log lvel. Thus, one can
now do Logger.getLogger("").setLevel(Level.FINER) and set the log level
for all other loggers (that do not specify their own default) to the
level specified.
if the System property rt.log.dir is set, standard logging messages are
written both to standard out and to the file log.txt inside the directory
provided. This allows us to get debugging information quickly.
