Romain Vimont authored Jun 16, 2021 and Jean-Baptiste Kempf committed Jun 22, 2021

The function DisplayPicture() handled both the frame-by-frame mode and
the "normal" mode (the mode depended on whether the deadline parameter
was NULL).

But almost the whole function is different for both cases, so use
separate functions.

Note: This commit is more comprehensible with:

    git show --patience -b