Updates the Field Item Editor to render layers based on the entire map, and the per-patch positioning of each layer.
Import/export will gracefully handle upgrade/downgrade, and viewport import/export will gracefully update tiles rather than a per-acre basis.
Performance has also been slightly improved; no allocation is done anymore when updating the image.
The second parameter of `Array.CopyTo` takes an integer that represents the index in array at which copying begins. Therefore in this case it should be set to 0 instead of the array's length.
Different means of expression for the 8 byte item structure's FreeParam
Will be expanding the ItemEditor so that it has a checkmark to toggle Extension Item editing behavior.
Removes IHeldItem as there's no need to abstract it.
Extracts logic from the building & terrain & field item editors for reuse / separation of concerns
Have FieldItemEditor select between Items & Terrain so that you can change the popup menu mode (view set delete)
Not sure how I want to show the terrain names...
