RGB stack can't handle differently sized images

[LTDakin]

Failing RGB stacks with the error
all the input array dimensions except for the concatenation axis must match exactly, but along dimension 0, the array at index 0 has size 2042 and the array at index 1 has size 2400

Best guess is that we are not cropping images before trying to stack or align them.

• figure out where error is being raised, either in align-fits, the code, fits2img or elsewhere
• patch it