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/
<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.38.2
Pidgin - Internet Messenger
Copyright (C) Pidgin Developers <devel@pidgin.im>
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
-->
<interface>
<requires lib="gtk+" version="3.22"/>
<!-- interface-license-type gplv2 -->
<!-- interface-name Pidgin -->
<!-- interface-description Internet Messenger -->
<!-- interface-copyright Pidgin Developers <devel@pidgin.im> -->
<template class="PidginPluginsMenu" parent="GtkMenu">
<property name="visible">True</property>
<property name="can-focus">False</property>
<child>
<object class="GtkMenuItem">
<property name="visible">True</property>
<property name="can-focus">False</property>
<property name="action-name">app.manage-plugins</property>
<property name="label" translatable="yes">Manage Plu_gins</property>
<property name="use-underline">True</property>
<accelerator key="u" signal="activate" modifiers="GDK_CONTROL_MASK"/>
</object>
</child>
<child>
<object class="GtkSeparatorMenuItem" id="separator">
<property name="can-focus">False</property>
</object>
</child>
</template>
</interface>