ArrayDataSet is the abstract base class for QDataSets which are backed by Java arrays For example, DDataSet is a QDataSet which uses a double array to store its data. Data is stored in 1-D Java arrays for performance, inspired by https://www.cs.cmu.edu/~artigas/papers/cacm01.pdf. Note for modern versions of Java, Arrays of Arrays are implemented with no performance cost. A number of static methods were initially defined in DDataSet, then copied into FDataSet and others when they were made. This super implementation will parent all such datasets and provide common methods.