Co-op synchronization and controls

• Save games can now be named from the main menu with the pencil button. The name persists after saving.
  
• Guests can once again craft items reliably in quick succession and deposit them into shared storage.
  
• Sails, rudders and raft movement now remain synchronized for both players without regular correction stutters.
  
• Waves, wind and floating debris are synchronized correctly when joining and during play.
  
• Existing traders, the Leviathan, raider boats, fish swarms and birds are now visible to players who join later.
  
• Switching save games no longer carries traders, the Leviathan or captured raider boats into the newly loaded world.
  
• The hook rope now starts at the correct launcher position when viewed on another player.
  
• If the Steam Overlay is unavailable, the invite button now opens a quieter fallback instead of showing a large error message.