TimestampDiff: Nanosecond is false by default

elements/analysis/timestampdiff.cc

@@ -56,7 +56,7 @@ int TimestampDiff::configure(Vector<String> &conf, ErrorHandler *errh)
             .read("OFFSET",_offset)
             .read("N", _limit)
             .read("MAXDELAY", _max_delay_ms)
-            .read("NANO", _nano)
+            .read_or_set("NANO", _nano, false)
             .read_or_set("SAMPLE", _sample, 1)
             .read_or_set("VERBOSE", _verbose, false)
             .read_or_set("TC_OFFSET", _tc_offset, -1)