cleanup build. add demo project. add timing features to sync. switch to more std::string and std::vector usage over custom, hacky Array template

inc/logger.hpp

@@ -0,0 +1,10 @@
+#pragma once
+
+#include <string>
+
+void log(const char* msg);
+void log(std::string msg);
+void log(char*, int len);
+void flush(const char* filepath);
+void start_auto_flush_thread(const char* filepath, double period);
+void start_auto_flush_thread();