Fix typo in in XmlImporte._check_if_namespace_meta_information_is_added which results in an exception.

In case it was required after the import to still add an ns an exception occured. On normal flow the line `_check_if_namespace_meta_information_is_added`s  with the typo isn't executed and no test was available to test the behaviour.

* Added test for `_check_if_namespace_meta_information_is_added`
* Fix the type

The typing information tries to use an no existing dataclass, requires an forward reference (escaped with single ').

The depends_on function result is an unrestricted recursive call when the depency is it self.

For completness, these datatypes are abstract! If they are used in structs, abstract types are either Variant or ExtensionObjects.
If they only contain basic types (int16, float, double..) they are Variants.

This reverts commit 80b63f17.

* check message limits on recv

* add ErrorMessage handling

* add to large chunk test

* client disconnect on ErrorMessage

* change default transport limits

* Initial new documentation

* Update server-minimal example which is used in the docs

* Better API Structure

* Added RTD Config

* Added documentation for 'a minimal opc-ua client'

* More about nodes and nodeids

* More usage guide

* Combined Node & NodeId Docu, updated links in index

* A little more documentation