Fixes & Improvements - v0.5.0.60

Needed to get an update out as became aware of trader bots not working. Thanks to LogrusUK for the info, along with a save slot issue details and a good idea of adding a new message notification sfx.

Patch notes:-

• Improve: New messages now gives a sound notification.
  
• Fix: Trader bot could have speed set to zero, so became stuck.
  
• Fix: Save selection incorrect when selecting different saves slots in one session.