pidgin/pidgin

Create new conversation when activating users in the new contact list

I also had to remove an unnecessary g_date_time_unref in the demo protocol
plugin for testing.

Testing Done:
Using the demo protocol plugin, I opened a conversation to `Echo` and sent a message. I then went to the buddy list window and double clicked on `Echo` again. I saw history got loaded, which I'll be removing in the near future, but I was able to send messages correctly.

Reviewed at https://reviews.imfreedom.org/r/2201/
REVIEWBOARD_URL = "https://reviews.imfreedom.org/"
REPOSITORY = "pidgin/pidgin"
REPOSITORY_TYPE = "mercurial"
BRANCH = "default"
LAND_DEST_BRANCH = "default"
LAND_PUSH = False