Give resource generate the capability to pad images rather than cropping them

[paulhickman-a365]

Add the moment if the resource generator has to create a rectangular image, it crops a rectangular section from the center of the supplied square source image.

It would be useful to add a 'pad' option - e.g. 'pad: "#ffffff" that supplies an RGB background colour.

When pad is used, the resource generator should create a solid rectangular image of the specified background colour and then paste the complete square source image into the center of the target.

Obviously, this would require support from the online image generator.