Same name Section or Property entities when setting name

[mpsonntag]

Currently appending a Section or a Property to a parent that already contains a Section or a Property with the same name fails. The unique names on the same hierarchical level are necessary since child Sections and Properties can be accessed by name, same name entities would lead to undefined behavior.

When setting the name of an existing Section or Property, there is no check for same name entities on the same hierarchical level. Setting the name of a Section or Property should be handled identical to name handling in append