Merged contrib folders from the graphbuilder-api branch, including the recursive search in CMakeLists.txt

src/contrib/graphbuilder.cpp

@@ -0,0 +1,16 @@
+#include "yaml-cpp/parser.h"
+#include "yaml-cpp/contrib/graphbuilder.h"
+#include "graphbuilderadapter.h"
+
+namespace YAML
+{
+  void *BuildGraphOfNextDocument(Parser& parser, GraphBuilderInterface& graphBuilder)
+  {
+    GraphBuilderAdapter eventHandler(graphBuilder);
+    if (parser.HandleNextDocument(eventHandler)) {
+      return eventHandler.RootNode();
+    } else {
+      return NULL;
+    }
+  }
+}