Added support for constructors and operators in sequence diagrams

tests/t20030/t20030.cc

@@ -0,0 +1,51 @@
+namespace clanguml {
+namespace t20030 {
+
+int magic() { return 42; }
+
+class A {
+public:
+    A() { create(); }
+
+    A(int v) { a_ = v; }
+
+    A &operator=(const A &a)
+    {
+        set(a.a_);
+        return *this;
+    }
+
+    A &operator+=(int a)
+    {
+        add(a);
+        return *this;
+    }
+
+    int value() const { return a_; }
+
+private:
+    void create() { a_ = 0; }
+
+    void add(int a) { a_ += a; }
+    void set(int a) { a_ = a; }
+
+    int a_;
+};
+
+void tmain(int a)
+{
+    A an_a{magic()};
+    an_a += 1;
+}
+
+int tmain(bool f, int a)
+{
+    auto an_a = A();
+    auto an_b = A();
+    an_a += 2;
+    an_b = an_a;
+    return an_b.value();
+};
+
+}
+}