Give rotation action an object argument

In the current version of the annotation interface, users can only annotate global block assembly rotations. But sometimes participants construct partial assemblies with multiple connected components and rotate one component independently of the others.

We can modify our formalism to describe this situation by making the rotation action take as an argument any block in the connected component that was rotated. This change entails:

• Updating annotationgui.py to create annotations with the new label format
• Updating markov_stats.py / duplostructure.py / libduplo.py to parse the new label format