Extend "Format Number" to support zero-padding

Improve the “format number” node to support zero padding of integers, useful for creating equal length output image sequence names.

Yes, that would be handy. And it’s trivial to add, so we’ll go ahead and schedule it for the upcoming Vuo 1.2 release.

In Vuo 1.2.0, we gave the Format Number node a Minimum Integer Digits input port.