[build] Extract proto generation with bootstrap plugin
Replaced treehugger with templates for generation, use dependent types in Message typeclass
Decoders from binary protobuf to scala-protobuf
Encoders from scala-protobuf to binary
Test protocol with source generated both for scala-protobuf and google-protobuf
Decoder tests with the test protocol
Scalacheck generator of arbitrary pairs of matching scala-protobuf and google-protobuf messages
Serialization and equivalence tests