0.06 [KK 2011-02-12] "make tarball" now versions the contained sources
     directory. Macro whether signal.h is present, is now properly
     propagated when compiling (was buggy). Thanks again Bram for reporting.

0.05 [KK 2010-12-23] Several smaller changes for Debian compatibility,
     Linux builds should now run ok, tarball versioning, etc. Thanks
     Bram Neijt for reporting.

0.04 [KK 2010-12-06] Back end checks will warn for failures during the
     first 5 checks, and then every 10th check. The other times it's
     only a debug message. This avoids spamming the output log.

0.03 [KK 2010-12-05] Changed SIGHUP (1) to show the back ends state
     (used to be to terminate). Debug state is now class-dependent and
     suppressed in the wake up calls, so that "dead" back ends don't
     clutter the log.

0.02 [KK 2010-12-01] Homogenous/heterogenous DNS back ends introduced.
     If you have DNS back ends that serve different zones and are not
     synchronized, then dnspb will try to resolve names using all the
     back ends and won't accept "name error" for an answer. To enable
     this, use flag --heterogenous-dns (-H). Normally dnspb will stop
     once it receives any answer, even a "name error".

0.01 [KK 2010-11-29] Initial alpha release.