create node settlement extension

This extension can be used to decide where to attach a newly created
node.
yes, though its not best practice to access the constant through a child class. but anyways, i agree that probably the DI thing (MappingStrategy sounds good to me, btw) can completely replace this.

if you need the class itself define its parent, you should go with a repository id strategy in phpcr-odm that asks the document to provide the id.