Changes to Interpretations for Appendices

This builds on top of #222, so please check that one first.

* AMDPARser extended to deal with interpretations of appendices (`resolve_confused_context`)
* Patches should clear their respective entries in the layer cache (so that hand-added images appear)
* When "and" occurs in an emphasized part of an AMD (which indicates it is a header), remove the "and", lest it trigger the logic in `and_token_resolution`
* Account for appendix citations of the form "appendix X, part IV.7.R"