Add Ticker library (#1057)

* Add Ticker library

* Fix CI (#1)

remove LED_BUILTIN in examples

libraries/Ticker/examples/Arguments/Arguments.ino

@@ -0,0 +1,27 @@
+#include <Arduino.h>
+#include <Ticker.h>
+
+// attach a LED to GPIO 21
+#define LED_PIN 21
+
+Ticker tickerSetHigh;
+Ticker tickerSetLow;
+
+void setPin(int state) {
+  digitalWrite(LED_PIN, state);
+}
+
+void setup() {
+  pinMode(LED_PIN, OUTPUT);
+  digitalWrite(1, LOW);
+  
+  // every 25 ms, call setPin(0) 
+  tickerSetLow.attach_ms(25, setPin, 0);
+  
+  // every 26 ms, call setPin(1)
+  tickerSetHigh.attach_ms(26, setPin, 1);
+}
+
+void loop() {
+
+}