update description of processors according to C++ guidelines

- need to have a virtual destructor so that the derived class's implementation will be called when
  it is destroyed via a pointer to the base class.
- use override and only override

src/using/analysis/analyzer-boilerplate.cxx

@@ -8,8 +8,8 @@ class MyAnalyzer : public framework::Analyzer {
   MyAnalyzer(const std::string& name, framework::Process& p)
     : framework::Analyzer(name, p) {}
   ~MyAnalyzer() = default;
-  void onProcessStart() final;
-  void analyze(const framework::Event& event) final;
+  void onProcessStart() override;
+  void analyze(const framework::Event& event) override;
 };
 
 void MyAnalyzer::onProcessStart() {

src/using/analysis/analyzer-total-rec-energy.cxx

@@ -8,8 +8,8 @@ class MyAnalyzer : public framework::Analyzer {
   MyAnalyzer(const std::string& name, framework::Process& p)
     : framework::Analyzer(name, p) {}
   ~MyAnalyzer() = default;
-  void onProcessStart() final;
-  void analyze(const framework::Event& event) final;
+  void onProcessStart() override;
+  void analyze(const framework::Event& event) override;
 };
 
 void MyAnalyzer::onProcessStart() {

src/using/config/structure-of-event-processors.md

@@ -38,19 +38,26 @@ class MyProducer : public Producer {
    */
   MyProducer(const std::string& name, Process& p) : Producer(name, p) {}
 
+  /**
+   * Destructor
+   * Marked virtual so that it will be called when MyProducer
+   * is destructed via a pointer of type Producer*
+   */
+  virtual ~MyProducer() = default;
+
   /**
    * Configure this instance of MyProducer
    *
    * We get an object storing all of the parameters set in the python.
    */
-  void configure(Parameters& params) final override;
+  void configure(Parameters& params) override;
 
   /**
    * Produce for the input event
    *
    * Here is where you do all your work on an event-by-event basis.
    */
-  void produce(Event& event) final override;
+  void produce(Event& event) override;
 
  private:
   /// a parameter we will get from python