Pacem JS - <pacem-hierarchy>

## Hierarchy Organizer
`PacemHierarchyElement` is the webcomponent that eases visual arrangement of hierarchical sets.

> Not to be confused with _TreeViews_, **Hierarchial Sets** are characterized by a "loose structure" that allows multiple parents.

> The hierarchy component shows the ancestors on the upper part of the stage and the descendants below.

## Structured Datasource and Value
`PacemHierarchyElement` expects a **datasource** as a flat set of items to arrange.

> The **value** is the actual hierarchical mapping.

The **value** gets merged with the **datasource** during the component's rendering process and the result is the visual hierarchy.  
The following properties are the - opinionated - "glue" for this merge:

- `valueProperty` (required): defines the name of the **numeric or textual** property in **both** the datasource and the value that allows to identify the items' relations (consider it as a _foreign key_).
- `parentsPropery` (defaults to _"parents"_): defines the name of the array property that carries the identifiers in the **value** object only.
- `textProperty` (optional): defines the name of the textual property that labels a datasource item when leaning on the default template.
- `disabledProperty` (optional): defines the name of the boolean property that may disable a datasource item.

## Interactivity
When not readonly, the `PacemHierarchyElement` permits you to:

- Link two items **that aren't already in an ancestor-descendant pipe** (drag the parent onto the child using the link icon).
- Remove a link between two items (middle-click on the visual binding).
- Move around the items to ease hierarchy readability (drag using the drag indicator).

> You cannot link nor unlink **disabled** items.