Use lambda instead of bind, it's semantically better and give the opportunity to the compiler to make better optimization.
Rename events and use more type alias to shorten the code.
Replace last bind by lambda and delete namespace ph alias.
Add license header for the chat example.
Fix include order.
Remove useless include and move chat_client constructor in the .cpp.
Better message formatting and add a safe console in a multithreading context.
Use unordered_map for clients in the server side, don't resend message to the client who sent it. Fix console printing.