DGIterator: Add unpack_field method
MessageDirector: Move channel_t to messages.h constants.
StateServer: Move unpack_field to util.
StateServer: Update <map> import
MDNetworkParticipant: Remove unused include.
StateServer: Fixed includes for clarity, from deletion in unpack_field
RoleFactory: Remove confusing and unused MessageDirector.h import.
Merge pull request #56 from OpenOTP/kestred

Misc Cleanup