Hey, a user of my [SVG Import Extension](https://github.com/xsrf/easyeda-svg-import) noticed that inner layers don't support Images / SVGNodes. While I do get the intention behind this (after all this is designed for Images an they are usually visible) I don't really see a reason to not support it. There obviously may be reasons why someone would import an image to inner layers. I don't think this requires a huge change, so could you consider supporting it? Thx!