add consts, and finish awful union structs.
add consts, and finish awful union structs.

jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm,jdelgadoalfonso/openpgm