Add support for X1 and X2 mouse buttons

app/src/main/java/com/limelight/Game.java

@@ -1010,6 +1010,24 @@ public class Game extends Activity implements SurfaceHolder.Callback,
                     }
                 }
 
+                if ((changedButtons & MotionEvent.BUTTON_BACK) != 0) {
+                    if ((event.getButtonState() & MotionEvent.BUTTON_BACK) != 0) {
+                        conn.sendMouseButtonDown(MouseButtonPacket.BUTTON_X1);
+                    }
+                    else {
+                        conn.sendMouseButtonUp(MouseButtonPacket.BUTTON_X1);
+                    }
+                }
+
+                if ((changedButtons & MotionEvent.BUTTON_FORWARD) != 0) {
+                    if ((event.getButtonState() & MotionEvent.BUTTON_FORWARD) != 0) {
+                        conn.sendMouseButtonDown(MouseButtonPacket.BUTTON_X2);
+                    }
+                    else {
+                        conn.sendMouseButtonUp(MouseButtonPacket.BUTTON_X2);
+                    }
+                }
+
                 // Get relative axis values if we can
                 if (inputCaptureProvider.eventHasRelativeMouseAxes(event)) {
                     // Send the deltas straight from the motion event
@@ -1360,6 +1378,12 @@ public class Game extends Activity implements SurfaceHolder.Callback,
         case EvdevListener.BUTTON_RIGHT:
             buttonIndex = MouseButtonPacket.BUTTON_RIGHT;
             break;
+        case EvdevListener.BUTTON_X1:
+            buttonIndex = MouseButtonPacket.BUTTON_X1;
+            break;
+        case EvdevListener.BUTTON_X2:
+            buttonIndex = MouseButtonPacket.BUTTON_X2;
+            break;
         default:
             LimeLog.warning("Unhandled button: "+buttonId);
             return;

app/src/main/java/com/limelight/binding/input/evdev/EvdevListener.java

@@ -4,6 +4,8 @@ public interface EvdevListener {
     int BUTTON_LEFT = 1;
     int BUTTON_MIDDLE = 2;
     int BUTTON_RIGHT = 3;
+    int BUTTON_X1 = 4;
+    int BUTTON_X2 = 5;
 
     void mouseMove(int deltaX, int deltaY);
     void mouseButtonEvent(int buttonId, boolean down);

app/src/root/java/com.limelight/binding/input/evdev/EvdevCaptureProvider.java

@@ -151,7 +151,15 @@ public class EvdevCaptureProvider extends InputCaptureProvider {
                                 break;
 
                             case EvdevEvent.BTN_SIDE:
-                            case EvdevEvent.BTN_EXTRA:
+                                listener.mouseButtonEvent(EvdevListener.BUTTON_X1,
+                                        event.value != 0);
+                                break;
+
+                            case EvdevEVent.BTN_EXTRA:
+                                listener.mouseButtonEvent(EvdevListener.BUTTON_X2,
+                                        event.value != 0);
+                                break;
+
                             case EvdevEvent.BTN_FORWARD:
                             case EvdevEvent.BTN_BACK:
                             case EvdevEvent.BTN_TASK: