This patch introduces some extra safety checks in journal processing,

This patch introduces some extra safety checks in journal processing,
and cleans up the code a little bit.

 * moved journal initialization to its own function; main() is cleaner

 * any time we process a file, log the results
   (previous code only loggded if there was a valid entry)

 * After reading journals at startup, only trigger full flush out to disk
   if the user specified -F.  Avoids unnecessary IO on startup unless the
   user also wants unnecessary IO on shutdown.

 * journal_replay is much more careful about files it will open
     * must be a regular file
     * must be owned by daemon user
     * must not be group/other writable

 * Ensure that the journal gets created with the right permissions.
    ... even when the daemon is invoked with a permissive umask.
    equivalent to "chmod a-x,go-w"

-- kevin

git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@1586 a5681a0c-68f1-0310-ab6d-d61299d08faa