Add wait() helper that doesn't sleep. Useful for repeaters and sensors that read from the network.

libraries/MySensors/MySensor.cpp

@@ -486,6 +486,23 @@ void MySensor::sleep(unsigned long ms) {
 	internalSleep(ms);
 }
 
+void MySensor::wait(unsigned long ms) {
+	bool slept_enough = false;
+	unsigned long start = millis();
+	unsigned long now;
+
+	// Let serial prints finish (debug, log etc)
+	Serial.flush();
+
+	while (!slept_enough) {
+		MySensor::process();
+		now = millis();
+		if (now - start > ms) {
+			slept_enough = true;
+		}
+	}
+}
+
 bool MySensor::sleep(uint8_t interrupt, uint8_t mode, unsigned long ms) {
 	// Let serial prints finish (debug, log etc)
 	bool pinTriggeredWakeup = true;

libraries/MySensors/MySensor.h

@@ -210,6 +210,15 @@ class MySensor : public RF24
 	 */
 	void sleep(unsigned long ms);
 
+	/**
+	 * Wait for a specified amount of time to pass.  Keeps process()ing.
+	 * This does not power-down the radio nor the Arduino.
+	 * Because this calls process() in a loop, it is a good way to wait
+	 * in your loop() on a repeater node or sensor that listens to messages.
+	 * @param ms Number of milliseconds to sleep.
+	 */
+	void wait(unsigned long ms);
+
 	/**
 	 * Sleep (PowerDownMode) the Arduino and radio. Wake up on timer or pin change.
 	 * See: http://arduino.cc/en/Reference/attachInterrupt for details on modes and which pin