Super Tiled2Unity 2.2.0

2.2.0 changes

• No longer creating and managing embedded sprite atlases. This allows uses to put tile sheets into sprite atlases of their choosing. ST2U now uses the original textures to make tiles.
• Improved error and warning reporting
• ST2U now uses "error tiles" when something goes wrong with importing textures or tilesets.
• Packaged zip is now compatible with Linux