Base: Move App::Color to Base

Every basic data type is stored in Base module, color is standing out as
one that does not. Moving it to Base opens possibilities to integrate it
better with the rest of FreeCAD.

src/Mod/Import/App/ExportOCAF2.h

@@ -51,7 +51,7 @@ namespace Import
 struct ImportExport ExportOCAFOptions
 {
     ExportOCAFOptions();
-    App::Color defaultColor;
+    Base::Color defaultColor;
     bool exportHidden = true;
     bool keepPlacement = false;
 };
@@ -60,7 +60,7 @@ class ImportExport ExportOCAF2
 {
 public:
     using GetShapeColorsFunc =
-        std::function<std::map<std::string, App::Color>(App::DocumentObject*, const char*)>;
+        std::function<std::map<std::string, Base::Color>(App::DocumentObject*, const char*)>;
     explicit ExportOCAF2(Handle(TDocStd_Document) hDoc,
                          GetShapeColorsFunc func = GetShapeColorsFunc());