Android ParallaxSwipeBack

带视觉差的侧滑返回，类似于新版微信和lofter的侧滑返回效果。核心代码小于50行.

Usage

`public class MainActivity extends ParallaxSwipeBackActivity {

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    findViewById(R.id.next).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(MainActivity.this,NextActivity.class);
            intent.putExtra("index",0);
            startParallaxSwipeBackActivty(MainActivity.this, intent);
        }
    });

}`