Feature request: support upscaling

[B. Kelly]

I'd like to use tiv to replace some uses that I already use timg for, since it generally produces better results; however, they require it to be able to emit images exactly scaled to fit the tty height. tiv's -w and -h settings only set upper bounds on the image size, though; it won't upscale.

[clort81]

you could write a wrapper script to use imagemagick to upscale image before running it through tiv.

[Stefan Haustein]

Perhaps we could add uppercase -W / -H to force a specific width or height?