Fix admin reindex typo (See #10031)
Close config early for reindexing (Fix #9800)
Handle multiple calls to omero.config.close()

The previous change in `bin/omero admin reindex` to close
the config early (See #9800) was failing with:

```
^CERROR:ConfigXml:Failed to removed lock file, ignoring
Traceback (most recent call last):
  File ".../lib/python/omero/config.py", line 154, in _close_lock
    os.remove("%s.lock" % self.filename)
OSError: [Errno 2] No such file or direc...
```
Make `bin/omero admin reindex` exit cleanly

Due to background threads, a call to System.exit() is necessary
to prevent needing a Ctrl-C on the console.
Fix whitespace in doc
Merge pull request #836 from joshmoore/rebased/develop/reindex-fixes

reindex bug fixing (rebased onto develop)