The new serialization format use "t " as in typed. The rest of the
message is a JSON array describing the typed data. The type is
described by types.TypeRef
Fixes#384
Issues #281, #304
The codegen.go command line utility now detects the package name from
the file that it was invoked from if `--package` was not provided.
It also processes all `.noms` files in the current directory in case
the `--in` flag was not provided.
