Demo Achievements* Update

The Back To The Dark demo is now updated with a collection of steam achievements to aim for whilst dungeon delving, gold ingots to consolidate treasure, mobs with increased difficulty in deeper levels, a little more tweaking of item drop rarity, and a couple of crash/bug fixes.

• Added 12 Steam Achievements. (*Sorry no non-steam interface for the achievements yet)
• Added gold ingots to shop.
• Increased enemy difficulty in deeper dungeon levels.
• Increased drop rarity in deeper dungeon levels.
• Added some statistics tracking e.g. number of escapes, deepest dungeon level reached.
• Fixed player hp not retained through red portals.
• Fixed dropped items appearing on top of the player.
• Fixed crash when "dropping" items in the tavern.
• Fixed game not pausing when opening steam overlay.