Bundler Tool: splicing of subobjects

[thomasfn]

• Allow subobjects (e.g. districts inside district maps, civic articles inside amendments etc) to be spliced and moved/copied in between parent objects, probably via dragging them in the tree view, and using them to create new objects (e.g. select some districts, right click and click "move to new district map").
• Other handy utilities like "convert amendment to constitution"
• Display law sections as subobjects in the tree and allow those to be spliced like above also