Open Allow 'Invisible Appearance Items' to function properly on vendors

Allow 'Invisible Appearance' items to function properly on vendors.

Currently, the only way to customize vendors is to 'drag' a clothing item onto them. But once you've dressed your vendor in an article of clothing, it is impossible to remove. This means that if you put, say, a jacket on a vendor, then they will now always be wearing a jacket. You can put a new jacket on them, but their jacket slot is now permanently occupied. This is true for all clothes/accessories.

If you try to put 'Invisible Appearance Item: Jacket' onto this vendor, instead of creating an 'invisible jacket' as on a player, it puts the default icon of the item onto the vendor--in this example, the appearance of the 'Casual Jacket' item--rather than neutralizing the appearance of the jacket slot as intended.

Making the galaxy just a bit more beautiful.