Add protobuf as a selection for sending raw data

[corenel]

Since the protobuf library supports varint-length encoding and decoding, maybe it's a better choice for our team to do team communication based on this protocol.

• Add implementation of sendProtobufRaw() and recvProtobufRaw()
• Test the length difference between the raw binary data and the one based on protobuf
• Test the encoding and decoding efficiency between the raw binary data and the one based on protobuf
• Test data in string type for the transmission latency
• Add string data in TeamInfo for displaying auxiliary messages (e.g., hardware warning, behavior route)

Maybe this improvement can be placed in the project for the next year (2020).