pbconv 0.5.4

A implement of Dart:convert for [Protobuf](https://developers.google.com/protocol-buffers/).

0.5.4

• maintance.

0.5.3

• Added to support Dart:Convert.

0.5.2

• Now it seems that most of the bugs have been solved.

0.5.1

• Some problems have been solved, mainly those brought about by the rewriting process.

0.5.1

• Conduct detailed tests to find problems.

0.5.0

• Convert my protobuf library from C++ to Dart, It's the initial version for Dart version protobuf.