Unify ImgLib2 Histogram implementations

[curtis]

There are currently multiple implementations of a histogram throughout ImgLib2 and KNIP. There is  one in net.imglib2.algorithm.stats, as well as another in [net.imglib2.script.analysis].

We need to fix up the net.imglib2.algorithm.stats.Histogram implementation to be flexible enough to cover all use cases. For example, it needs to support using any Iterable<T> rather than only Img<T> or RealCursor<T>.

[bdezonia]

Note that there is a Histogram2D class in imglib2 OPS

[aivar]

These histogram implementations mix the basic idea of making a histogram with a means of traversing the image.

The core value to histogram bin assignment should be refactored to use the new Binning class:

 https://github.com/imagej/imglib/blob/master/imglib2/core/src/main/java/net/imglib2/Binning.java

Unfortunately the extant histogram variants involve a pass through the image. This is not very efficient if you want to find the image minimum and maximum and then build a histogram of values in that range. I added a ticket #1384.

[bdezonia]

Christian mentioned that there is also an OpsHistogram class in imglib2 OPS.

[bdezonia]

I have been doing some work on this for our most recent beta on imglib's histogram-stuff branch. Soon I'll share with others and solicit feedback.

[bdezonia]

The histogram changes I made are in Imglib's master branch in the Imglib2 algorithms subproject in the histogram subpackage. Further work is needed by users of Imglib to utilize the new histogram classes. Clsogin this ticket.