Feature/show every element

These changes let the user see every Entities on which he has clicked because they can be on top of each other.

src/core/Core.hpp

@@ -451,6 +451,21 @@ public:
     void selection_information(const std::string &) const override {
     }
 
+    /*!
+     * \brief Only use in graphic interface.
+     */
+    void selection_information_clear() const override { }
+
+    /*!
+     * \brief Only use in graphic interface.
+     */
+    void selection_information_show() const override { }
+
+    /*!
+     * \brief Only use in graphic interface.
+     */
+    virtual void selection_information_new_tab(const std::string &) const override { }
+
     /*!
      *\brief Set the minimum for export
      *\param d The double.