Wolf logging macro

Notice: This PR is only about simple wolf logging macro as described below and do not implement any data logging as this topic as to be discussed. A data logging draft class is implemented on branch wolf_data_logging.

Enable logging macro using third-party spdlog (MIT license) :

• WOLF_INFO
• WOLF_WARN
• WOLF_ERROR
• WOLF_DEBUG (enabled only if compiled in debug)
• WOLF_TRACE (which is the same as WOLF_DEBUG_HERE but enabled/disabled at compile time)

Trace logging is enabled/disabled from the src/CMakeLists.txt option

option(_WOLF_TRACE "Enable wolf tracing macro" OFF)

test_wolf_logging.cpp shows the following:

  WOLF_INFO("test info ", 5, " ", 0.123);
  WOLF_WARN("test warn ", 5, " ", 0.123);
  WOLF_ERROR("test error ", 5, " ", 0.123);
  WOLF_TRACE("test trace ", 5, " ", 0.123);
  WOLF_DEBUG("test debug ", 5, " ", 0.123);

Which, full feature enabled, produces :

The log pattern is :
[thread id][hour:min:sec.nanosec][log type] log-content

The TRACE log pattern is :
[thread id][hour:min:sec.nanosec][log type][$file l#$line : $function] log-content

src/logging.h

@@ -48,6 +48,9 @@ public:
   template<typename... Args>
   void debug(const Args&... args);
 
+  template<typename... Args>
+  void trace(const Args&... args);
+
   void enable_debug(const bool enable);
 
   bool enable_debug();
@@ -93,6 +96,10 @@ Logger::Logger()
   enable_debug(true);
 #endif
 
+#ifdef _WOLF_TRACE
+  console_->set_level(spdlog::level::trace);
+#endif
+
   // Enable asynchronous logging
   // Queue size must be a power of 2
   spdlog::set_async_mode(4096);
@@ -131,6 +138,12 @@ void Logger::debug(const Args&... args)
   console_->debug(repeat_string("{}", sizeof...(args)).c_str(), args...);
 }
 
+template<typename... Args>
+void Logger::trace(const Args&... args)
+{
+  console_->trace(repeat_string("{}", sizeof...(args)).c_str(), args...);
+}
+
 inline void Logger::enable_debug(const bool enable)
 {
   (enable)? console_->set_level(spdlog::level::debug) :
@@ -180,7 +193,7 @@ inline bool Logger::set_async_queue(const std::size_t q_size)
 #ifdef _WOLF_TRACE
   #define WOLF_TRACE(...) \
     char this_file[] = __FILE__;\
-    WOLF_WARN("[", basename(this_file), " l#", __LINE__, \
+    wolf::internal::Logger::get().trace("[", basename(this_file), " l#", __LINE__, \
               " : ", __FUNCTION__, "] ", __VA_ARGS__)
 #else
   #define WOLF_TRACE(...)