Several compilation fixes for MSVC and NVCC, basically:

- added explicit enum to int conversion where needed
- if a function is not defined as declared and the return type is "tricky"
  then the type must be typedefined somewhere. A "tricky return type" can be:
  * a template class with a default parameter which depends on another template parameter
  * a nested template class, or type of a nested template class

Eigen/src/Cholesky/Cholesky.h

@@ -147,7 +147,7 @@ typename Derived::Eval Cholesky<MatrixType>::solve(const MatrixBase<Derived> &b)
   * \returns the Cholesky decomposition of \c *this
   */
 template<typename Derived>
-inline const Cholesky<typename ei_eval<Derived>::type>
+inline const Cholesky<typename MatrixBase<Derived>::EvalType>
 MatrixBase<Derived>::cholesky() const
 {
   return Cholesky<typename ei_eval<Derived>::type>(derived());

Eigen/src/Cholesky/CholeskyWithoutSquareRoot.h

@@ -159,7 +159,7 @@ typename Derived::Eval CholeskyWithoutSquareRoot<MatrixType>::solve(const Matrix
   * \returns the Cholesky decomposition without square root of \c *this
   */
 template<typename Derived>
-inline const CholeskyWithoutSquareRoot<typename ei_eval<Derived>::type>
+inline const CholeskyWithoutSquareRoot<typename MatrixBase<Derived>::EvalType>
 MatrixBase<Derived>::choleskyNoSqrt() const
 {
   return derived();