Make FeaturesViewer available in Viewer2D to display the feature points of the current view, based on the current FeatureExtraction node.
* FeaturesInfoOverlay: overlay that displays info and provides controls over a FeaturesViewer component.
* ColorChart: color picker based on a set of predefined colors.
Introduce a new TextFileViewer component with auto-reload feature based on a ListView instead of a TextArea for performance reasons. Uses the text content split on line breaks as ListView's model.
Features:
* auto-scroll to bottom
* display line numbers
* customizable line delegates (e.g.: display a real progress bar)
* color lines according to log level
* use it in MetadataListView and GraphEditor 'add Node' menu
* GraphEditor: forward MenuItem key events to searchBar to be able to continue editing the filter even if it lost active focus
