Other than what action they send back to
EmulationActivity.handleMenuAction(), they are the same.
Change the menu-handling logic in EmulationActivity to keep track of a
boolean for whether the submenu is visible, rather than keeping the
fragment tag. There's only one fragment visible, so this makes more
sense.
Prefixing everything with a constant packagename is not needed for
internal keys, and just adds complexity.
Rename ARGUMENT_ prefix to ARG_ to match (most) of the rest of the
codebase.
Restrict visiblity of above as much as possible.
FRAGMENT_ID wasn't actually the fragment's ID (that's misleading, and
sounds like the tag). It's actually the layout resource ID. There's no point in making that a static constant.