Added SyslogFormatter.

Similar to the FuncMessageFormatter, but include the TID and don't add a
newline at the end.

Author: ceggers-arri

include/plog/Formatters/SyslogFormatter.h

@@ -0,0 +1,30 @@
+#pragma once
+#include <plog/Record.h>
+#include <plog/Util.h>
+#include <utility>
+
+namespace plog
+{
+    class SyslogFormatter
+    {
+    public:
+        static util::nstring header()
+        {
+            return util::nstring();
+        }
+
+        static util::nstring format(const Record& record)
+        {
+            util::nostringstream ss;
+            ss << PLOG_NSTR("[") << record.getTid() << PLOG_NSTR("] ")
+               << record.getFunc() << PLOG_NSTR("@") << record.getLine()
+               << PLOG_NSTR(" ") << record.getMessage() /* no line feed */;
+
+#if __cplusplus > 201703L
+            return std::move(ss).str();
+#else
+            return ss.str();
+#endif
+        }
+    };
+}