Performance optimization

If you think our app is great, please give us a five-star rating. We specially improved the performances related to file transfer.
1.Supported transferring extra-large files exceeding 20G.
2.Improved stability: transferring hundreds of thousands of files and contacts nonstop for 24 hours with no mistake.

1. IPv6 perfectly supported;
2. Some bug fixed.

Bugs fixed and many improvements.

1. Interface optimized.
2. Add feature "Find devices in Same Wi-Fi"

fix bugs.