Add scale option for page break pad height

[timup]

This adds an option to the opt parameter, scale. Scale is intended as a multiplier for the page break pad height. In my use case, I am creating a canvas twice as wide as the eventual pdf, so that charts render in their full width, however this influences the page break feature - the page height is only 1/2 the height needed, when I have doubled the width.

The screenshot shows the result- where the page break pad is only 1/2 the height that it needs to be. I'm sure there's a better way to name this, or a more universal way to work this in, so I am open to any suggestions and can rework this as needed.

[timup]

It looks like #170 handles this same issue... perhaps in a better way.

[timup]

Yes - #170 handles this, but without the need for an additional option.