Added scheduler example using millis()

lab3/lab3_demo_scheduler_without_delay/lab3_demo_scheduler_without_delay.ino

+const unsigned task1Period = 500; /* iga 500 ms järel */
+const unsigned task2Period = 250; /* iga 100 ms järel */
+
+void setup() 
+{
+  Serial.begin(9600);
+}
+
+void loop() 
+{
+  static uint32_t task1LastRun = 0;
+  static uint32_t task2LastRun = 0;
+
+  uint32_t currentTime = millis();
+
+  /* Ülesannet lahendatakse iga 500 ms järel  */
+  if (currentTime - task1LastRun >= task1Period)
+  {
+    task1LastRun = currentTime;
+    Serial.print(millis() / (float)1000);
+    Serial.println(" Olen Boe-Bot");
+  }
+
+  /* Ülesannet lahendatakse iga 250 ms järel */
+  if (currentTime - task2LastRun >= task2Period)
+  {
+    task2LastRun = currentTime;
+    Serial.print(millis() / (float)1000);
+    Serial.println(" Beep-Boop");
+  }
+}