It turns out that specifying height and width explicitly
does not guarantee that the image protocols will actually fill
the specified space. Notably iterm will honor aspect ratio
(which is good), but leave the cursor where the image would
naturally leave it (which is difficult with relative positioning).
Previously, relative positioning was used as a workaround
for the fact that save/restore or any absolute positioning may
be fouled by incurring scroll.
To make cursor save/restore work, we determine the total rows and
print newlines enough to incur scroll and then move cursor back up.
This lets us use save/restore to ignore cursor movement by the image.
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