1- Introduce sub-evaluator types for unary, binary, product, and map expressions to ease specializing them.

2- Remove a lot of code which should not be there with evaluators, in particular coeff/packet methods implemented in the expressions.

Eigen/src/Core/ArrayBase.h

@@ -123,7 +123,11 @@ template<typename Derived> class ArrayBase
     EIGEN_DEVICE_FUNC
     Derived& operator=(const ArrayBase& other)
     {
+#ifndef EIGEN_TEST_EVALUATORS
       return internal::assign_selector<Derived,Derived>::run(derived(), other.derived());
+#else
+      internal::call_assignment(derived(), other.derived());
+#endif
     }
 
     EIGEN_DEVICE_FUNC