added turtle program

docs/examples/turtle.md

@@ -0,0 +1,52 @@
+# Turtle
+
+A fun interactive program where the user enters a sequence of moves using the buttons and the robot executes it.
+
+
+```blocks
+/**
+* Run this program with a driving base.
+**/
+let indent = ""
+let command = ""
+let c = ""
+brick.buttonLeft.onEvent(ButtonEvent.Pressed, function () {
+    command = command + "L"
+})
+brick.buttonRight.onEvent(ButtonEvent.Pressed, function () {
+    command = command + "R"
+})
+brick.buttonUp.onEvent(ButtonEvent.Pressed, function () {
+    command = command + "F"
+})
+brick.buttonDown.onEvent(ButtonEvent.Pressed, function () {
+    command = command + "B"
+})
+brick.buttonEnter.onEvent(ButtonEvent.Pressed, function () {
+    indent = ""
+    for (let index = 0; index <= command.length; index++) {
+        c = command[index]
+        brick.showString("" + indent + c, 4)
+        indent = "" + indent + " "
+        if (c == "L") {
+            motors.largeBC.steer(-100, 50, 378, MoveUnit.Degrees)
+        } else if (c == "R") {
+            motors.largeBC.steer(100, 50, 378, MoveUnit.Degrees)
+        } else if (c == "F") {
+            motors.largeBC.steer(0, 50, 1, MoveUnit.Rotations)
+        } else if (c == "B") {
+            motors.largeBC.steer(0, -50, 1, MoveUnit.Rotations)
+        }
+    }
+    command = ""
+    brick.showString("", 2)
+})
+motors.largeBC.setBrake(true)
+forever(function () {
+    brick.showString("TURTLE", 1)
+    brick.showString(command, 3)
+    brick.showString("up/down: forward/backward", 8)
+    brick.showString("left/right: turn", 9)
+    brick.showString("enter: play commands", 10)
+})
+```