Added previews to image autocomplete inputs

[orangemug]

Added a nice preview of the sprites in the image autocomplete

Note: Max width of 120px for the preview image, incase there is a large image in the sprite, will scale the image preview if larger.

@pathmapper I'm going to leave this as in draft for now, I think we should resolve #711 and push out a new release first before merging.

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[pathmapper]

@orangemug cool, very helpful!

push out a new release first before merging

Yep, think so, too.

.