Added message ids to action messages

Added message ids to action messages, apparently that made them exactly the same as regular messages. 

Maybe we could introduce `enum message_type {plain_message, action_message}`, add an extra byte to the message sending function to include that enum and use a single message sending and processing function, instead of having several identical copies? (with this pull request `m_sendmessage` == `m_sendaction`, `m_sendmessage_withid` == `m_sendaction_withid`, `case: PACKET_ID_MESSAGE` == `case: PACKET_ID_ACTION`) We can keep the tox API the same and use enums only internally, or propagate them into the API and merge `m_sendmessage*` and `m_sendaction*` into a single function with an `enum message_type` as a parameter.