Range selection behaviour not consistent with scatter plot expectation. Unable to remove all selections.

The RangeSelection tool appends selection masks to a list held in the datasource metadata. When removing the selection, the tool deletes all items in the selection_mask list, however, it remains as an empty list in the datasource metadata.

When rendering selected points, the scatterplot renderer checks for the existence of a metadata field named 'selection_masks' if it exists, it will collect the points to be rendered. Unfortunately, it doesn't handle the case of an empty list which is what is left by the RangeSelection tool.