add autocompleted names to private chats
add autocompleted names to private chats

Fix #1459

https://github.com/thelounge/lounge/issues/1459

Add rawNicks() to more easily get the list of nicks for the current
channel or chat without overly complicating its caller.

MaxLeiter/lounge,MaxLeiter/lounge,ScoutLink/lounge,realies/lounge,MaxLeiter/lounge,FryDay/lounge,ScoutLink/lounge,williamboman/lounge,williamboman/lounge,thelounge/lounge,williamboman/lounge,FryDay/lounge,thelounge/lounge,FryDay/lounge,ScoutLink/lounge,realies/lounge,realies/lounge