Refactored comment parsing to clang comments

tests/t00002/.clang-uml

@@ -5,6 +5,7 @@ diagrams:
     type: class
     glob:
       - ../../tests/t00002/t00002.cc
+    comment_parser: clang
     using_namespace:
       - clanguml::t00002
     include:

tests/t00002/t00002.cc

@@ -3,7 +3,7 @@
 namespace clanguml {
 namespace t00002 {
 
-/// This is class A
+/// \brief This is class A
 class A {
 public:
     /// Abstract foo_a
@@ -12,7 +12,7 @@ public:
     virtual void foo_c() = 0;
 };
 
-/// This is class B
+/// \brief This is class B
 class B : public A {
 public:
     virtual void foo_a() override { }