Use class enums and constants rather than global enums and define

Fix a bug : virtual transferts must not be considered as a debit

src/model/User.cpp

@@ -56,7 +56,7 @@ Category User::GetCategory(const wxString& catId)
     cat.parent = wxT("0");
     cat.name = _("Unknown");
     cat.font = wxT("");
-    cat.backcolor = OWN_GREEN;
+    cat.backcolor = view::OWN_GREEN;
     cat.forecolor = wxColour(0x00, 0x00, 0x00);
 
     return cat;