support for external fmtlib

include/spdlog/fmt/fmt.h

@@ -0,0 +1,28 @@
+//
+// Copyright(c) 2016 Gabi Melman.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+//
+
+#pragma once
+
+//
+// Include a bundled header-only copy of fmtlib or an external one.
+// By default spdlog include its own copy.
+// 
+
+#if !defined(SPDLOG_FMT_EXTERNAL)  
+
+#ifndef FMT_HEADER_ONLY
+#define FMT_HEADER_ONLY
+#endif
+#ifndef FMT_USE_WINDOWS_H 
+#define FMT_USE_WINDOWS_H 0
+#endif 
+#include <spdlog/fmt/bundled/format.h>
+
+#else //external fmtlib
+
+#include <fmt/format.h>
+
+#endif 
+