Added a class 'array' which provides the same functionality as FixedArray, but...

Added a class 'array' which provides the same functionality as FixedArray, but conforms to the naming
of the tr1 array class.  I would have liked to put this into a separate header, but unfortunately,
array.hh exists already.  In a future step, the stl implementation of 'array' will be used when
available.

[[Imported from SVN: r4895]]