This namespace contains element specific logic.
It defines the different element categories of model elements and views
and the hierarchical relationships. The namespace also defines predicates
to query the elements and functionality requiring only elements or collections
of elements without references to the model as a whole.

Functions for the definition and handling of the overarch model.

The loaded overarch working model is a map with these keys:

:input-elements         -> the given data
:nodes                  -> the set of nodes (incl. child nodes)
:relations              -> the set of relations (incl. contains relations)
:views                  -> the set of views
:themes                 -> the set of themes
:id->element            -> a map from id to element (nodes, relations and views)
:id->parent             -> a map from id to parent element
:referrer-id->relations -> a map from id to set of relations where the id is the referrer (:from)
:referred-id->relations -> a map from id to set of relations where the id is referred (:to)

Functions for the definition and handling of views.