Base/App: fix warnings from code analysers:

* convert old-style-casts to explicit C++ casts where possible
* make some implicit conversions explicit

src/Mod/Mesh/App/Core/Visitor.h

@@ -24,7 +24,8 @@
 #ifndef VISITOR_H
 #define VISITOR_H
 
-#include "Definitions.h"
+#include <vector>
+#include <Base/Vector3D.h>
 #include <Mod/Mesh/MeshGlobal.h>
 
 namespace MeshCore {
@@ -32,6 +33,7 @@ namespace MeshCore {
 class MeshFacet;
 class MeshKernel;
 class MeshFacetVisitor;
+class MeshPoint;
 class PlaneFit;
 
 /**