v0.15.1 - Trade fixes & improvements

Changelog:

• Trade panel 
  • Fixed value modifier for negative valued items
  • Added ribbons showing if item price is under/over priced
• All item prices were increased x2
• Added button to undock visitor (visitor and dock port panels)
• Added click sound to more places
• Voice informs about obtaining new technology
• Water Purifier device is now under Survival category

New trade panel: