Implement missing restart method for dG3D and msch IPVariables

Solver/STensor33.h

@@ -102,6 +102,9 @@ class STensor33 {
     return *this;
   }*/
   void print(const char *) const;
+
+  const double* data() const{return _val;}
+  double* data() {return _val;}
 };
 
 // tensor product

Solver/STensor43.h

@@ -153,6 +153,8 @@ class STensor43 {
     return *this;
   }*/
   void print(const char *) const;
+  const double* data() const {return _val;}
+  double* data() {return _val;}
 };
 
 // tensor product