import19: add target namespace parameter

[UlrichB22]

... and fix itemlink migration for subitems (e.g. for users namespace)

Related to #1597.

[ClaasTeichmann]

I tested import19 with my wikifarm and found several issues, which I am listing here:

Missing directories

I have to create the missing directories:

wiki01/data
wiki01/meta

before converting.

User directories

User directories are stored in moin19 in

common/user

They are expected by the import routine in
wiki01/data/user

Solution:

cd wiki01/data/
ln -s ../../common/user .

Alternatively, it could be good to provide an additional parameter to specify the user-directory.

Groups

In moin19 each wiki in the farm had its own EditorGroup, AdminGroup, etc.
Now, to separate the EditorGroups, it would be good to convert the EditorGroup to Wiki01EditorGroup.
The wikiconfig.py has to be adapted accordingly.

Do I understand it correctly that different wikis with different users are separated now by using different namespaces?

Missing Link

This, e.g., pdf cannot be found:

http://127.0.0.1/namespace01/Page01/Attachment01.pdf

It can be found here, thus the namespace information is missing:

http://127.0.0.1/Page01/Attachment01.pdf

Mind that the page is created correctly here:

http://127.0.0.1/namespace01/Page01

EditorGroup doesn't exist

The page

http://127.0.0.1/EditorGroup

doesn't exist and cannot be created.