scheduling of clients, so that one client cannot starve other clients
for resources.  (Bug 102).  Run the database save, garb, and check for
killed clients from three separate liboop timer callbacks.  Use liboop
for signal dispatching.  Use liboop.  (Bug 106).  Code cleanup.
Renamed a few constants that have nothing to do with ISC.  Make it
possible to read an unsigned int from the config file.  Add SA_RESTART
support to liboop.  (This has been sent to the liboop maintainer.)
(Fixes bug 845).  Add a few utility string functions.