More customization for text scrolling

[xeruf]

timg sometimes allows to scroll text-files, but this functionality is very limited:
From my observations, the file has to end in .txt, even then usually ImageMagick creates a picture instead (which can be prevented with -V), yet not all text-files that ImageMagick would convert are actually scrolled in the end:

Furthermore, none of the "Scrolling" flags have any effect whatsoever.

In theory, this text scrolling is a great way to take stock of a bunch of files, but it would be good if it could be explicitly enabled for any file not recognized specifically as media regardless of extensions, and scroll speed customized. An option to only scroll until the image frame is filled would also be nice (which in my experiments usually occurs after 3 frames).