[Bug Fix] Forgotten include added.
[Code Style] Comment and code style.
[Aux] Code reordering.
[TCP] Write handler will now block until the message is completely sent.
[Code Style] Reordering.
[Thread Safety] Socket sink's thread-safety is now properly handled.
[Aux] Refactoring over socket sink.

 - Exporting public typedefs.
 - Renaming.
[Code Style] Style.
[Code Clean] Refactoring done over tcp backend.

 - Export public typedefs.
 - Removed deprecated member fields prefix.
 - Code style.
[Code Clean] The similar refactoring over udp backend.
[Thread Safety] All sinks are now thread-aware.