Include what is used in pybind11.h (#2499)
* Include what is used
* Separated the C++ standard library headers and the project headers
* Reordering includes
diff --git a/include/pybind11/pybind11.h b/include/pybind11/pybind11.h
index 617c01f..7c5286a 100644
--- a/include/pybind11/pybind11.h
+++ b/include/pybind11/pybind11.h
@@ -46,6 +46,11 @@
#include "detail/class.h"
#include "detail/init.h"
+#include <memory>
+#include <vector>
+#include <string>
+#include <utility>
+
#if defined(__GNUG__) && !defined(__clang__)
# include <cxxabi.h>
#endif