Provide the ability to straighten images in the client

[jadrake75]

For a while, users have requested the ability to straighten/auto-correct the orientation of a stamp in the image. This is not meant to address camera pictures taken at random angles, but stamps on a sheet that are slightly skewed (0-10 degrees) when scanned with a flat-bed scanner. In theory, ImageJ can provide the skewness factor that can be leveraged to determine the correction required.

Has been deferred to date due to lack of sponsorship and not being needed by author.

[Xanir]

HTML5 Canvas naively supports rotation, so that could be an option.