Use recursive config patching

[mkfrey]

• More flexible patching
• Better readable code

[mkfrey]

This PR will make the config patching algorithm recursive.
This results in the following benefits:

• The patching code is easier to read
• The storage footprint is lower
• All future changes to the config structures and config depth should be covered

The patching has the following behaviour:

• If an element in the patch does not exist in the current config, it will be set to the patch element.
• If an element in the patch is not an object or the element in the current config is not an object, it will be set to the patch element.
• If an element in the patch is an object and the element in the current config is an object all described steps will be repated with these two objects.

[mkfrey]

Please don't merge yet. With the password being optional after merging #647, I can rewrite the patching to support the removal of configuration values by setting them to null in the patch.

[stritti]

@codefrey could you rebase to branch develop please?
Renaming the branches closed the PR. Sorry.