Change inheritance tree so that <T>Matrix inherit from <T>NDArray. * liboctave/array/CMatrix.cc, liboctave/array/CMatrix.h, liboctave/array/CNDArray.cc, liboctave/array/CNDArray.h, liboctave/array/dMatrix.cc, liboctave/array/dMatrix.h, liboctave/array/dNDArray.cc, liboctave/array/dNDArray.h, liboctave/array/fCMatrix.cc, liboctave/array/fCMatrix.h, liboctave/array/fCNDArray.cc, liboctave/array/fCNDArray.h, liboctave/array/fMatrix.cc, liboctave/array/fMatrix.h, liboctave/array/fNDArray.cc, liboctave/array/fNDArray.h: change base class of Matrix, FloatMatrix, ComplexMatrix, and FloatComplexMatrix to NDArray, FloatNDArray, ComplexNDArray, and FloatComplexNDArray respectively. This will allow to reduce duplicated code since the Matrix classes will be able to inherit many of their methods from their NDArray counterparts. Also remove the matrix_value () method since a constructor now suffices. * liboctave/array/CSparse.h: include CMatrix * libinterp/corefcn/pr-output.cc, libinterp/octave-value/ov-cx-mat.cc, libinterp/octave-value/ov-flt-cx-mat.cc, libinterp/octave-value/ov-flt-re-mat.cc, libinterp/octave-value/ov-re-mat.cc: replace calls to matrix_value () with constructor with respective Matrix subclass.

--- a/liboctave/array/fCNDArray.cc
+++ b/liboctave/array/fCNDArray.cc
@@ -826,20 +826,6 @@
   return *this;
 }
 
-FloatComplexMatrix
-FloatComplexNDArray::matrix_value (void) const
-{
-  FloatComplexMatrix retval;
-
-  if (ndims () == 2)
-    retval = FloatComplexMatrix (Array<FloatComplex> (*this));
-  else
-    (*current_liboctave_error_handler)
-      ("invalid conversion of FloatComplexNDArray to FloatComplexMatrix");
-
-  return retval;
-}
-
 void
 FloatComplexNDArray::increment_index (Array<octave_idx_type>& ra_idx,
                                       const dim_vector& dimensions,