Add a timer to turn off after a period of time. Move the LED name to reduce string literals.

src/Timer.cpp

@@ -0,0 +1,32 @@
+#include <Arduino.h>
+
+class Timer{
+private:
+	unsigned long _interval, _lastTick;
+	void (*_callback)(void);
+	bool _running;
+
+public:
+	Timer(void (*callback)(void)){
+		_callback = callback;
+		_running = false;
+	}
+
+	void reset(unsigned long interval){
+		_interval = interval;
+		_lastTick = millis();
+		_running = true;
+	}
+
+	void loop(){
+		if (!_running)
+			return;
+			
+		unsigned long tick = millis();
+
+		if (tick - _lastTick >= _interval){
+			_callback();
+			_running = false;
+		}
+	}
+};