Protoparse cannot parse group inside oneof

[bufdev]

This is actually valid Protobuf:

// a.proto

syntax = "proto2";

message Foo {
  oneof bar {
    group Baz = 1 {
      optional int64 bat = 2;
    }
  }
}

• protoc a.proto -o /dev/null completes successfully
• goprotoc a.proto -o /dev/null returns a.proto:7:19: syntax error: unexpected '{', expecting ';' or '['

[jhump]

Weird. I did not know that they extended group support to oneofs. I guess I should read that part of the protoc code more closely...

I think it should be pretty easy to fix, luckily.

[jhump]

Fixed in #262