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
Add dependencies when used as a plugin to configuration file.

Define the various dependencies and information when the
client is used a a plugin.
Move user notification to main class.
Remove whitespace in dependencies list.
Handle the fact that the tag can have not child nodes.
Add support for and/or when checking dependencies list.
Adjust warning message depending on the conjunction used.
Indicate when dependencies are used.
Ignore dependencies if used as Fiji plugin.
Do not set the namespace to an empty string (see #10393)
Add tests to check namespace.
Remove get and set namespace methods

The methods already exists in AnnotationData.
No need to override them.
Replace true by equals.
Introduce omero.constants.DEFAULTBLOCKSIZE

Use of MESSAGESIZEMAX (64MB in kb) was seriously affecting
performance on upload of FS files. This commit introduces
DEFAULTBLOCKSIZE at 5MB in byte.

A further option would be to make it configurable via etc/ice.config.
Fix whitespace in client.{h,cpp}
Remove owner check if userID < 0 (see #10482)