Stretched input image in output image

[hexaclue]

Currently, if the input image is not exactly square, the image will be stretched to a square ratio, to fill the available space. This is in almost 100% of the cases not what a user wants.

Possible fixes:

• Center the input image
• Let the user choose where the input image belongs in the image (requires more work, but may satisfy the user more)

[hexaclue]

In v2.0.0, the default behaviour is a BoxFit of cover, instead of fill. May need some work, as to be able to change the fit to other types