imglib2-core: a new Type, UnsignedAnybitType, with arbitrary bit depth.

One could consider Unsigned12bitType a special case of this new type,
which is totally inspired and generalized from it.
imglib2-core: test for UnsignedAnyBitType
As expected, the larger the number of bits, the worse the performance:

Unsigned12BitType: 726 ms
UnsignedAnyBitType for 12 bits: 2013 ms

BitType: 258 ms
UnsignedAnyBitType for 1 bit: 364 ms

UnsignedShortType: 252 ms
UnsignedAnyBitType for 16 bits: 3457 ms
imglib2-core: UnsignedAnyBitType now has getBigInteger.
Also minor fixes to minimize method calls, assuming
long is the preferred return type (the JVM is optimized for it).
imglib-core: UnsignedAnyBitType.setBigInteger
imglib2-core: faster implementation for UnsignedAnyBitType.setBigInteger
imglib2-core: UnsignedAnyBitType .inc() and .dec() with tests.
imglib2-core: UnsignedAnyBitType got its own RealType math methods
which wrap around or crop on overflow.
imglib2-algorithms: IntegralHistogram for 1d and 2d images.
The tests show that it works, but further testing is necessary.
imglib2-algorithms: moved IntegralHistogram to scripting package,
much easier testing.
imglib2-scripting: first attempt at a RandomAccess+Cursor that accesses
the histograms at each pixel by computing them from the integral histogram
image.
imglib2-scripting: documentation on Histograms and also fixes.
imglib2-scripting: HistogramFeatures is an image that gets filled
with the result of computing various image features such as min, max, mean,
by approximating them from the histogram values.

Currently broken.
imglib2-scripting: fixed numerous issues with IntegralHistogram.
imglib2-scripting: IntegralHistogram contains IntegerType samples.
imglib2-scripting: Histograms is able to iterate properly.
imglib2-scripting: HistogramFeatures cleaned up a bit, still doesn't give correct results.
imglib2-scripting: tests for piece-wise testing of integral histograms
imglib2-scripting: fixed hopefully all errors in integral histograms and their features.
imglib2-scripting: integral histogram and features without the debugging.
imglib2-scripting: make Histograms return a long[]
instead of an Img<LongType>