Change the inner iterations logic

This replace the Boolean switch to enable inner iterations with a
int that controls for which maximum number of newton iterations
inner iterations applies.

Default is set to 3

opm/simulators/wells/WellInterface.hpp

@@ -279,8 +279,6 @@ public:
                            const GroupState& group_state,
                            DeferredLogger& deferred_logger);
 
-    virtual bool useInnerIterations() const = 0;
-
 protected:
 
     // simulation parameters