Allow scaling down to 5% in popover scale dialog

[peppy]

Request from mapper IRL.

[OliBomby]

How about letting it go down to 0% or even negative? Such scaling values would also produce valid results. I think 0% could be useful while scaling on a single axis to squash the axis, or turn a pattern into a stack.

[peppy]

The issue with letting it go lower would be that the slider bar gets silly.

It would need to be textbox entry only. You're welcome to propose a diff for that, I wasn't willing to put in the effort without a user request because it's more complicated.

[bdach]

This didn't actually work properly. I have made it work with f616c7b.

[OliBomby]

The issue with letting it go lower would be that the slider bar gets silly.

You mean it would get silly for negative values right? For 0% minimum scaling it shouldn't make much of a difference to the slider bar since that only makes the range 0.5% bigger.