Number type fields should specify types of numbers intended (in documentation comment)

[janerivi]

Even though JavaScript will handle a wide range of number types under the "number" type static languages needs to specify type of float or integer value (float32 vs double64 vs Int vs Int64 vs UInt etc). So whenever a number field exists in the protocl spec there should be a comment indicating what type of number the field shall contain. @jamesjackson