Improve the collapse/expand functionality?

[Siderite]

So at this moment the collapse/expand variation menus are there for all moves, although for some it doesn't work. And for those where it works it's not clear what will be collapsed or expanded.

A good fix would be to remove the menu items where they don't make sense and provide some visual representation of what would happen when you hover over the remaining meu items.

[Siderite]

Maybe one can even persist the collapse/expand settings selected manually by the user over page refreshes. In that case remember that this applies to studies as well as analyzed games (including running correspondence games)