Extract wrappers around Paper.js items from stencils.
Finish extract Paper.js wrappers and bring them under test.
Rename Paper.js wrappers to viewmodels/paths rather than viewmodels/paper
Refactored stencils, simplifying the way in which properties are passed to paths.
Update TODO list.
Revisited tests for stencils now that some of the logic has moved onto paths.
Fix bug with deleting paths.