Fix for #927 OrientationHelper.enable() called twice (#928)

* Update OrientationHelper.java

Fixed issue #927 Added boolean to prevent listener activating multiple times.

* Update CameraView.java

Added disable() of the orientation helper class in onPause.

* Update OrientationHelper.java

Co-authored-by: Mattia Iavarone <mat.iavarone@gmail.com>

cameraview/src/main/java/com/otaliastudios/cameraview/CameraView.java

@@ -855,6 +855,7 @@ public class CameraView extends FrameLayout implements LifecycleObserver {
     @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)
     public void close() {
         if (mInEditor) return;
+        mOrientationHelper.disable();
         mCameraEngine.stop(false);
         if (mCameraPreview != null) mCameraPreview.onPause();
     }

cameraview/src/main/java/com/otaliastudios/cameraview/internal/OrientationHelper.java

@@ -37,6 +37,8 @@ public class OrientationHelper {
     @VisibleForTesting
     final DisplayManager.DisplayListener mDisplayOffsetListener;
     private int mDisplayOffset = -1;
+    
+    private boolean mEnabled;
 
     /**
      * Creates a new orientation helper.
@@ -97,6 +99,11 @@ public class OrientationHelper {
      * Enables this listener.
      */
     public void enable() {
+        if (mEnabled) {
+            //already enabled, will ignore call
+            return;
+        }
+        mEnabled = true;
         mDisplayOffset = findDisplayOffset();
         if (Build.VERSION.SDK_INT >= 17) {
             DisplayManager manager = (DisplayManager)
@@ -110,6 +117,8 @@ public class OrientationHelper {
      * Disables this listener.
      */
     public void disable() {
+        if (!mEnabled) return;
+        mEnabled = false;
         mDeviceOrientationListener.disable();
         if (Build.VERSION.SDK_INT >= 17) {
             DisplayManager manager = (DisplayManager)