RenderParameter image size adaptation methods are not always consistent

[sschoenborn]

RenderParameter has three methods to adapt to image size:

• withImageSize: changes the sampling rate of the image, affects the resolution of the rendering -- works as intended
• forImageSize: crops or enlarges view without changing the face's size. Does distort the face when the original aspect ratio is not square
• fitToImageSize: should adapt the size of the image by scaling and padding to match the new size best without distorting the face. Distorts the face if the original aspect ratio is not square

The methods do not always work if the original image size is not square