Change naming convention of class properties

src/core/include/Logger.hpp

@@ -23,9 +23,9 @@ class Logger {
 
     class Sink {
         private:
-        bool lineIsPrefixed_;
-        Logger& parent_;
-        const Logger::Level level_;
+        bool _lineIsPrefixed;
+        Logger& _parent;
+        const Logger::Level _level;
         void prefixLine(bool resetToFalse = false);
         public:
         Sink(const Level level, Logger& parent);