MT::LCWriter writes old format files

[fdplacido]

When writing files using the MT::LCWriter, the format seems to be old.
When checking the number of events with lcio_event_counter one gets the following:

$ lcio_event_counter examples/cpp/rootDict/DST01-06_ppr004_bbcsdu.slcio
 LCIORandomAccessMgr::getEventMap() recreating event map for direct access (old file)
49

which is one event less than it should (off by 1).

This happens with the *.slcio files found in this repo, within the examples folder, and files written using MT::LCWriter.
When using the regular writer lcio_event_counter reports correctly.