* Formatted protocol and its docstrings
* Fixed some docstrings in shared and state
* Fixed google style docstrings in addresses
* More docstrings and formatting fixes in highlevelcrypto and shutdown
* .readthedocs.yml
* When clicking a link in a message viewed in HTML mode, if the link represents a data blob, launch a "Save File" dialog and write the file directly, rather than opening the link in an external browser.
* Add "Attach File" button to message composition.
* pylint fixes.
