Choose how to split overlapping polygons

When splitting multiple polygons using the "direct split workflow" we cannot handle overlapping polygons.

Workaround is to:
1. Use bbox selection to select the overlapping polygons
2. Use the table view to refine the selection to only the polygons that requiring splitting
3. Use the split tool; it will only operate against the polygons selected above

Recommended solution is to create a "split view" as the opposite of the merge view. This would allow users to review the features involved; and place a checkbox next to each one that should be included in the split.

A split view is preferable to a dialog as it allows the user to continue to work with the map. As features are selected in the split view; the existing functionality to "flash" a selected feature can offer visual confirmation.