option to store image snapshot in title svg file

It would be a nice feature if when creating a title, an image snapshot of the current position of the video being edited were (optionally) stored in the SVG file, so that when edited with inkscape, it would be possible to exactly align the overlay with the image, and have arrows pointing at different parts of the image, etc.

After saving the SVG file, however, openshot would (should) just ignore the 'alignment' image in the SVG file.