Removed last artefact of checkCellExistence (in constructor taking wells)

Somehow this slipped one of the merges. With the last
patch this module failed to compile as we use the new
definition without the bool parameters.

opm/core/wells/WellsManager.hpp

@@ -66,7 +66,7 @@ namespace Opm
         /// manage control switching does not exist.
         ///
         /// @param[in] W Existing wells object.
-        explicit WellsManager(struct Wells* W, bool checkCellExistence=true);
+        explicit WellsManager(struct Wells* W);
 
         /// Construct from input deck and grid.
         /// The permeability argument may be zero if the input contain