CW: Mapping content after copying structural element

This MR fixes #1153 (closed),

Description

the internal link block linkage is not working properly after copying, because it contains the target element which does not exist in the new copied element. Therefore, it is required to have a mapping in a way that it could happen in the top level of structural element.

Solution

The design is to provide a comprehensive mapping in the structural element which can be used not only for the link block but for further mapping as well. Using a static mapping variable and giving a mapping ID will help to have more control over the contents mapping in one object. After the copying of containers, blocks and children is done, we perform the mapping in the parent (most top copied struct element). For further mapping implementation, the method preformMapping can be used and expanded. NOTE: regarding link block mapping, the design is to perform the map if it is available, if not then leave it empty, so that it does not mess up with the structure.