[Feature] Add Support for Layered Images

[solarProtag]

Currently the language plugin does not have any part of layered images in its dictionary. This makes it tedious to work with layered images. The sublime plugin, which is linked as a reference, does have layered image support so it's strange the vscode plugin doesn't.

[duckdoom5]

Ah good to know. I thought I had covered that, but clearly it's still missing pieces.

I'll look into it when I find the time

[solarProtag]

Thank you for the quick response!