Gyro tutorials (#930)

* gyro tutorials

* tutorials

* fix gyro simulator

* images

* updated image

* fix svg errors

libs/gyro-sensor/docs/reference/sensors/gyro/calibrate.md

@@ -1,6 +1,6 @@
 # calibrate
 
-Reset the zero reference for the gyro to current position of the brick.
+Detects if the gyro is drifting and performs a full reset if needed.
 
 ```sig
 sensors.gyro2.calibrate()

libs/gyro-sensor/gyro.ts

@@ -73,7 +73,7 @@ namespace sensors {
         }
 
         /**
-         * Forces a calibration of the with light progress indicators. 
+         * Detects if calibration is necessary and performs a full reset, drift computation.
          * Must be called when the sensor is completely still.
          */
         //% help=sensors/gyro/calibrate
@@ -95,6 +95,19 @@ namespace sensors {
             // give time for robot to settle
             pause(700);
 
+            // compute drift
+            this.computeDriftNoCalibration();
+            if (Math.abs(this.drift()) < 0.1) {
+                // no drift, skipping calibration
+                brick.setStatusLight(StatusLight.Green); // success
+                pause(1000);
+                brick.setStatusLight(statusLight); // resture previous light
+
+                // and we're done
+                this.calibrating = false;
+                return;
+            }
+
             // calibrating
             brick.setStatusLight(StatusLight.OrangePulse);