Merge image and grid to make a new picture

[markkanen89]

This feature would be great to have because then we can make the image and grid align the way we want it before creating a new image which we can send to a separate monitor.

We might need a backend for this to work correctly.

[markkanen89]

This has been semi-fixed. They open in a new page, but as soon as we resize the settings are overwritten. We'll look into populating the controls on document load from what's in the svg.
It's not only the grid-controls but also image rotation that is reset on redraw.