Image Servers: Declare supported file formats

[arildm]

In the decision of which image server software to employ, it would help a lot if this overview would outline the image file formats that are supported by the various servers.

For instance, I find that IIPImage only supports JPEG2000 and tiled TIFF.

[triplingual]

This would be helpful but needs a volunteer to take on some combination of independent research and contacting the image server maintainers.