Putting pretty much everything into a function

- "Externalizing" all the calls for drawing and displaying into functions,
so we don't have to repeat ourselves.
- Images can now be padded if wanted
- The synthetic images don't need to be square, thus PatternSize is now
  an 2D array.
- `pep8`ify this thing!

TODO: Plotting of the MTF (line through FFT) for the real image is not
      correct, we need to work on that a bit more...