- add _packetCoeff() to Inverse, allowing vectorization.

- let Inverse take template parameter MatrixType instead
  of ExpressionType, in order to reduce executable code size
  when taking inverses of xpr's.
- introduce ei_corrected_matrix_flags : the flags template
  parameter to the Matrix class is only a suggestion. This
  is also useful in ei_eval.

Eigen/src/Core/MatrixBase.h

@@ -511,8 +511,8 @@ template<typename Derived> class MatrixBase
       * \code #include <Eigen/LU> \endcode
       */
     //@{
-    const Inverse<Derived, true> inverse() const;
-    const Inverse<Derived, false> quickInverse() const;
+    const Inverse<typename ei_eval<Derived>::type, true> inverse() const;
+    const Inverse<typename ei_eval<Derived>::type, false> quickInverse() const;
     Scalar determinant() const;
     //@}