New cpp folder structure

Signed-off-by: Alexander Borsuk <me@alex.bio>

libs/routing/joint.cpp

@@ -0,0 +1,23 @@
+#include "routing/joint.hpp"
+
+#include <sstream>
+
+namespace routing
+{
+// static
+Joint::Id constexpr Joint::kInvalidId;
+
+std::string DebugPrint(Joint const & joint)
+{
+  std::ostringstream oss;
+  oss << "Joint [";
+  for (size_t i = 0; i < joint.GetSize(); ++i)
+  {
+    if (i > 0)
+      oss << ", ";
+    oss << DebugPrint(joint.GetEntry(i));
+  }
+  oss << "]";
+  return oss.str();
+}
+}  // namespace routing