Separate menus into vegan, vegetarian, others

Separate menus into vegan ones, vegetarian ones, and others. For each of these there is a section header with the appropriate emoji (this is no longer displayed for the individual menu items). Menu category headers are displayed once per section (e.g. "Wok" may appear both under vegan and others).

This also separates out some functionality into their own functions, including some mild clean-up. This was just to help make this change happen and to help me understand the code somewhat better.