draft implementation of alternative CameraBridge via GLES

a simple sample will look like:

```java
public class MainActivity extends Activity implements CameraGLSurfaceView.CameraTextureListener {

	CameraGLSurfaceView mView;
	ByteBuffer buf;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON,
                WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);

        mView = new CameraGLSurfaceView(this, null);
        mView.setCameraTextureListener(this);
        setContentView(mView);
        buf = ByteBuffer.allocateDirect(1920*1080*4);
    }

    @Override
    protected void onPause() {
        mView.onPause();
        super.onPause();
    }

    @Override
    protected void onResume() {
        super.onResume();
        mView.onResume();
    }

	@Override
	public void onCameraViewStarted(int width, int height) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onCameraViewStopped() {
		// TODO Auto-generated method stub

	}

	@Override
	public boolean onCameraFrame(int texIn, int texOut, int width, int height) {
		Log.i("MAIN", "onCameraFrame");
		int w=width, h=height;
		/*
		// option 1:
		// just return 'false' to display texIn on screen
		retutn false;
		*/

		/*
		// option 2:
		// fast copy texIn to texOut
		GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
    	GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texOut);
		GLES20.glCopyTexImage2D(GLES20.GL_TEXTURE_2D, 0, GLES20.GL_RGBA, 0, 0, w, h, 0);
		return true;
		*/

		// option 3:
		// read, modify and write back pixels
		GLES20.glReadPixels(0, 0, w, h, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buf);

		buf.rewind();
		// red line
		for(int i=0; i<h; i++) {
			buf.position(w*4*i+i*4);
			buf.put((byte) -1);
			buf.position(w*4*i+i*4+4);
			buf.put((byte) -1);
		}
		buf.rewind();

		GLES20.glActiveTexture(GLES20.GL_TEXTURE0);
    	GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, texOut);
		GLES20.glTexSubImage2D(GLES20.GL_TEXTURE_2D, 0, 0, 0, w, h, GLES20.GL_RGBA, GLES20.GL_UNSIGNED_BYTE, buf);
		return true;
	}
}
```

modules/java/generator/src/java/android+CameraGLSurfaceView.java

+package org.opencv.android;
+
+import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
+import org.opencv.core.Mat;
+
+import android.app.Activity;
+import android.content.Context;
+import android.opengl.GLSurfaceView;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import android.view.SurfaceHolder;
+import android.widget.TextView;
+
+public class CameraGLSurfaceView extends GLSurfaceView {
+
+    public interface CameraTextureListener {
+        /**
+         * This method is invoked when camera preview has started. After this method is invoked
+         * the frames will start to be delivered to client via the onCameraFrame() callback.
+         * @param width -  the width of the frames that will be delivered
+         * @param height - the height of the frames that will be delivered
+         */
+        public void onCameraViewStarted(int width, int height);
+
+        /**
+         * This method is invoked when camera preview has been stopped for some reason.
+         * No frames will be delivered via onCameraFrame() callback after this method is called.
+         */
+        public void onCameraViewStopped();
+
+        /**
+         * This method is invoked when delivery of the frame needs to be done.
+         * The returned values - is a modified frame which needs to be displayed on the screen.
+         * TODO: pass the parameters specifying the format of the frame (BPP, YUV or RGB and etc)
+         */
+        public boolean onCameraFrame(int texIn, int texOut, int width, int height);
+    };
+
+    private CameraTextureListener mTexListener;
+    private CameraRenderer mRenderer;
+
+    public CameraGLSurfaceView(Context context, AttributeSet attrs) {
+        super(context, attrs);
+
+        /*if(android.os.Build.VERSION.SDK_INT >= 21)
+            mRenderer = new Camera2Renderer(this);
+        else*/
+            mRenderer = new CameraRenderer(this);
+
+        setEGLContextClientVersion(2);
+        setRenderer(mRenderer);
+        setRenderMode(GLSurfaceView.RENDERMODE_WHEN_DIRTY);
+    }
+
+    public void setCameraTextureListener(CameraTextureListener texListener)
+    {
+        mTexListener = texListener;
+    }
+
+    public CameraTextureListener getCameraTextureListener()
+    {
+        return mTexListener;
+    }
+
+    @Override
+    public void surfaceCreated(SurfaceHolder holder) {
+        super.surfaceCreated(holder);
+    }
+
+    @Override
+    public void surfaceDestroyed(SurfaceHolder holder) {
+        super.surfaceDestroyed(holder);
+    }
+
+    @Override
+    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
+        super.surfaceChanged(holder, format, w, h);
+    }
+
+    @Override
+    public void onResume() {
+        super.onResume();
+        mRenderer.onResume();
+    }
+
+    @Override
+    public void onPause() {
+        mRenderer.onPause();
+        super.onPause();
+    }
+
+    @Override
+    public boolean onTouchEvent(MotionEvent e) {
+        if(e.getAction() == MotionEvent.ACTION_DOWN)
+            ((Activity)getContext()).openOptionsMenu();
+        return true;
+    }
+}