pidgin/pidgin

Use G_DECLARE_DERIVABLE_TYPE for PurpleConversation and additional cleanups

The setters for PurpleConversation are kind of crappy because of the
conversation cache in the purple_conversations api, which we'll address at a
later time.

Testing Done:
Compiled and ran locally, parted a chat and just signed out to verify no new issues.

Reviewed at https://reviews.imfreedom.org/r/613/
/* This file is part of the Project Athena Zephyr Notification System.
* It contains source for the ZCompareUID function.
*
* Created by: Robert French
*
* Copyright (c) 1987 by the Massachusetts Institute of Technology.
* For copying and distribution information, see the file
* "mit-copyright.h".
*/
#include "internal.h"
int
ZCompareUID(ZUnique_Id_t *uid1, ZUnique_Id_t *uid2)
{
return (!memcmp((char *)uid1, (char *)uid2, sizeof (*uid1)));
}