- remove Eval/EvalOMP (moving them to a disabled/ subdir in order

to preserve SVN history). They are made useless by the new
  ei_eval_unless_lazy.
- introduce a generic Eval member typedef so one can do e.g.
  T t; U u; Product<T, U>::Eval m; m = t*u;

disabled/Eval_MatrixType.cpp

@@ -0,0 +1,13 @@
+typedef Matrix3i MyMatrixType;
+MyMatrixType m = MyMatrixType::random(3, 3);
+cout << "Here's the matrix m:" << endl << m << endl;
+typedef Eigen::Eval<Eigen::Block<MyMatrixType,1,MyMatrixType::ColsAtCompileTime> >::MatrixType MyRowType;
+// now MyRowType is just the same typedef as RowVector3i
+MyRowType r = m.row(0);
+cout << "Here's r:" << endl << r << endl;
+typedef Eigen::Eval<Eigen::Block<MyMatrixType> >::MatrixType MyBlockType;
+MyBlockType c = m.corner(Eigen::TopRight, 2, 2);
+// now MyBlockType is a a matrix type where the number of rows and columns
+// are dynamic, but know at compile-time to be <= 2. Therefore no dynamic memory
+// allocation occurs.
+cout << "Here's c:" << endl << c << endl;