Minor bugs in dbck regarding file version conversion.

src/server/ChangeLog

+Wed Jul 24 03:05:48 1996  Per Cederqvist  <ceder@link>
+
+	* dbck.c (main): Die with an error message if an unsupported
+	output format version is requested.
+
+	* dbck-cache.c (cache_sync): Don't write 'I' records in version 0
+	files.  Ignore 'I' records in version 0 files, but warn about
+	them.
+
 Mon Jul 22 11:38:08 1996  David Byers  <davby@sen2.ida.liu.se>
 
 	* ram-output.c (foutput_conf_type): Output anarchy, rsv1, rsv2