make sure shuffling doesn't cause nested indices to be overwritten
make sure index changes can be propagated through conditional sections
allow empty string keypath in mappings
keypaths shouldn't be falsey in viewmodel register
because it makes the node test fail, but not the same code in the browser?
Merge pull request #1460 from evs-chris/gh-1457

Make sure shuffling doesn't cause index changes to propagate to levels referencing a deeper index
Merge pull request #1461 from evs-chris/gh-1442

Allow empty string keypath in mappings
merge with dev to resolve special ref resolution conflicts

Conflicts:
	src/virtualdom/items/shared/Resolvers/SpecialResolver.js