Resize - Constrain Proportions

[C-Lodder]

Just saw the improvements GIF @laoneo showed on Twitter

In the resize settings, you can change the width and height, and it seemed that when using the range bar to change the width, the height was changing accordingly.

It would be nice to have a switcher to enable/disable the constrain proportions, as the user may want to only change the width (without the height changing)

I can submit a PR if this is of interest

[laoneo]

Go for it!

[schnuti]

I tested today and I found the strict proportion restriction as a problem. I also believe it should be possible to enlarge the width and/or height. A few pixels might be needed.