Select geo-units that are completely surrounded by selection

[tgilcrest]

When drawing with the rectangle tool, the tool selects any shapes that it touches. When large shapes are selected they can easily cover large geographies that can surround smaller geo-units. However the smaller units are not selected, so they create small unassigned islands in the middle of a selection. We should change the selection so that small geo-units that are surrounded by a larger selected shape are also included in the selection.

Screenshot

E.g. Using the rectangle tool excludes these smaller areas that are surrounded by the selected areas. However, there is area beyond the unselected areas that are included, so it seems like the smaller areas should be included.