"From clipboard" button: fall back to interpreting clipboard data as path to image
Though we can currently paste into the Filename field, this is not useful for pasting a path, as it strips all '/'.
Some way to load directly from a path would be helpful. The "From Clipboard" button seems like the logical place to put it, as pressing this button with a path on the clipboard currently just produces an error flash.
This would enable browsing through project files in a real image viewer (eg. sxiv) and easily loading them in grafx2.
Ideally, the case of 'exactly 2 paths on the clipboard' could also be handled (replacing both the current page and the spare page)