Allow customization of image processing options

[uschmidt83]

Hi and thanks for the great and well documented theme!

One issue I had was that the author image and the page thumbnail images were quite hard to get right. Looking at the code, I learned that the Fill method with anchor Smart is used to resize and crop the images. This essentially guesses the region to crop the source image, which I found to be very unpredictable when trying to modify the source image to get the desired result. When using anchor Center, it is very predictable to prepare the source image to get the desired effect.

Hence, it would be great if there was a way to customize this behavior. I saw that it's possible to set Hugo's image processing defaults (including "anchor"), but the theme's article-link.html template explicitly uses the "smart" anchor to prepare the "feature" image, hence changing the default would have no effect.

All other uses of Fill within other theme templates do use Hugo's image processing defaults.

What do you think? Am I the only one with this issue?