Serial: Add basic tests for throughput and latency

java/libraries/serial/test/serial_throughput/arduino/serial_thoughput.ino

@@ -0,0 +1,9 @@
+void setup() {
+  Serial.begin(115200);
+}
+
+void loop() {
+  while (true) {
+    Serial.write('.');
+  }
+}

java/libraries/serial/test/serial_throughput/serial_throughput.pde

@@ -0,0 +1,32 @@
+import processing.serial.*;
+Serial serial;
+int start;
+byte[] in = new byte[32768];
+long num_ok = 0;
+long num_fail = 0;
+long num_recv = 0;
+
+void setup() {
+  println(serial.list());
+  // change this accordingly
+  serial = new Serial(this, serial.list()[0], 115200);
+  start = millis();
+}
+
+void draw() {
+  background(255);
+  if (0 < serial.available()) {
+    int recv = serial.readBytes(in);
+    for (int i=0; i < recv; i++) {
+      if (in[i] == '.') {
+        num_ok++;
+      } else {
+        num_fail++;
+        println("Received "+num_fail+" unexpected bytes");
+      }
+      num_recv++;
+    }
+  }
+  fill(0);
+  text(num_recv/((millis()-start)/1000.0), 0, height/2);
+}