allow multiple threads on one post

right now you can only create 1 thread per post. it would be nice to be able to have the ability to create multiple to keep things from getting cluttered.

example:

(current state)

message: party planning

—— thread: details

(desired state)

message: party planning

—— thread: guests

—— thread: menu

—— thread: location scouting

—— thread: contact numbers