Prevent instantiation of utility classes
Remove OldCalibratedSpace classes

This class was replaced with the new CalibratedSpace et. al hierarchy.

There have now been three ImgLib2 releases (2.0.0-beta-10, 2.0.0-beta-11
and 2.0.0-beta-12) including the deprecated OldCalibratedSpace, which is
hopefully a sufficient window to migrate existing code to the new API.
IntervalUtils, SpaceUtils: add missing javadoc
IntervalUtils, SpaceUtils: clean up style