Support proto wrapper types

[tiziano88]

Built-in wrapper types should be supported natively by the compiler.

e.g. IntValue could be represented as int option (or whatever the corresponding type is in OCaml -- sorry I'm not familiar enough with the language).

Also note that according to the proto specification, such types should be supported natively for JSON conversion, see https://developers.google.com/protocol-buffers/docs/proto3#json (i.e. they should be converted to the corresponding nullable field in JSON, rather than as a nested message (not sure if that's the case in your impl already).

ref. tiziano88/elm-protobuf#1

[mransan]

@tiziano88 this is definitely needed and I agree with you it should be supported. I'll work on a possible solution.

[XVilka]

Were there any developments about this?