Expose test's #if as command line parameter

[dzenanz]

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If the else part works, this #if should be exposed as a command line parameter and invoked as a new test case.

[dzenanz]

I finally got around to take a look at the entire code, and this is the only remark I have.

[Leengit]

That test might be resurrected with a little work. More generally, we should add a test with 3D images. Also, some examples from DigitalSlideArchive would be useful.