Hardware acceleration and code clean-up

• Hardware acceleration enabled by simply replacing Bitmap.setPixel within 2x loops to Canvas.drawRect, how could they draw pixels mannually like that... Now it's 20 times faster.
• Tried to solve (some of) memory leak problem by using lots of WeakReference and making AsyncTasks static. Still pretty much leaks that we've no idea about.
• Support for MCPE 1.2.13+ chunk format rewritten in Java, to overcome the fucking JNI latency and better fit into the existing design pattern.
• All features works for new level format now.
• Sorry but in previous release we filled the packageName wrong, so uninstall previous version if you had it installed from release page of this git repository.
• Ignore the strange characters below.
• 使用了支持硬件加速的渲染方式，应该比之前快20倍左右；解决了部分内存泄漏但是反复使用还可能OOM崩溃；上次填错了包名，如果从这个Github项目下载了之前的版本，需要手动卸载。