Added unit tests for array data and minor improvements.

Added unit tests for array data and minor improvements.

Added unit tests for AnalysisArrayData and some non-trivial methods in
AbstractAverageHistogram.  The analysis data test framework now contains
a method for filling an array data object from test input data.

Also fixed some issues in AbstractAnalysisArrayData, made read-only
accessors in public, added a few more methods to extract information,
and made the class use std::vector internally for memory management
instead of snew/sfree.

Part of issue #823.

Change-Id: I1d768e2763861f326b4e5a7cb94f5f82f0d56a9e