Provides a framework for connecting document regions with annotations and for displaying those.

## Package Specification

`IAnnotationModels` manage `Annotations`. When an annotation model is connected to an `IDocument`, any change to the document is reflected in the position of the managed annotations. Implementers of `IAnnotationModelListener` registered with an `IAnnotationModel` object get informed about changes of the model in respect to annotations.

`ISourceViewer` defines the concept of a document based, editable viewer supporting visual annotations. `ISourceViewer` supports document-specific and viewer-specific annotations attached to the viewer's input document. An `ISourceViewer` uses an `IAnnotationModel` to manage annotations and to inform implementers of `IAnnotationModelListener` about changes in respect to annotations. An `IVerticalRuler` represents an `IAnnotationModel` access adapter for an SWT widget capapble of display annotations. This package also provides default implementations for all defined interfaces.