remove multiplayer button

[pandrr]

• [x] always show cursors, add selection area (again) later
• [x] never show "join" or "leave"
• [x] remote viewer per user
• [x] do not sync patches between users, only to remote client
• [x] add "view remote client" to multiplayer icon
• [x] keep chat as is
• [x] reconnect to remote client on patch reload, sync full patch to remote client on pageload
• [x] remove "pilot"-fighting

next step: show in which subpatch the user is