lazy view version of imrotate/imresize

[johnnychen94]

imrotate is a high-level interface to warp. WarpedView is a lazy version of warp, and it makes sense to also have a lazy version of imrotate built on top of WarpedView.

When tweaking the performance, the lazy version is usually a good choice because:

• it does not allocate new memory for the entire array
• it does not compute the result for all pixels (only happens when you fetch it via getindex)

The lazy version is not always the best choice because if you call getindex repeatedly, the computation happens repeatedly.

Edit:

Similarily, we can support lazy imresize.