add: spdlog and basic client code.

3rd/spdlog/fmt/ranges.h

@@ -0,0 +1,23 @@
+//
+// Copyright(c) 2016 Gabi Melman.
+// Distributed under the MIT License (http://opensource.org/licenses/MIT)
+//
+
+#pragma once
+//
+// include bundled or external copy of fmtlib's ranges support
+//
+#include <spdlog/tweakme.h>
+
+#if !defined(SPDLOG_USE_STD_FORMAT)
+    #if !defined(SPDLOG_FMT_EXTERNAL)
+        #ifdef SPDLOG_HEADER_ONLY
+            #ifndef FMT_HEADER_ONLY
+                #define FMT_HEADER_ONLY
+            #endif
+        #endif
+        #include <spdlog/fmt/bundled/ranges.h>
+    #else
+        #include <fmt/ranges.h>
+    #endif
+#endif