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/
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<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN"
"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" [
]>
<chapter id="chapter-signals-plugin">
<title>Plugin signals</title>
<refsect1 id="plugins.signals" role="signal_proto">
<title role="signal_proto.title">List of signals</title>
<synopsis>
&quot;<link linkend="plugins-plugin-load">plugin-load</link>&quot;
&quot;<link linkend="plugins-plugin-unload">plugin-unload</link>&quot;
</synopsis>
</refsect1>
<refsect1 id="plugins.signal-details" role="signals">
<title role="signals.title">Signal details</title>
<refsect2 id="plugins-plugin-load" role="signal">
<title>The <literal>&quot;plugin-load&quot;</literal> signal</title>
<programlisting>
void user_function (PurplePlugin *plugin,
gpointer user_data)
</programlisting>
<para>
Emitted when a plugin is loaded.
</para>
<variablelist role="params">
<varlistentry>
<term><parameter>plugin</parameter>&#160;:</term>
<listitem><simpara>The plugin that was loaded.</simpara></listitem>
</varlistentry>
<varlistentry>
<term><parameter>user_data</parameter>&#160;:</term>
<listitem><simpara>user data set when the signal handler was connected.</simpara></listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2 id="plugins-plugin-unload" role="signal">
<title>The <literal>&quot;plugin-unload&quot;</literal> signal</title>
<programlisting>
void user_function (PurplePlugin *plugin,
gpointer user_data)
</programlisting>
<para>
Emitted when a plugin is unloaded.
</para>
<variablelist role="params">
<varlistentry>
<term><parameter>plugin</parameter>&#160;:</term>
<listitem><simpara>The plugin that was unloaded.</simpara></listitem>
</varlistentry>
<varlistentry>
<term><parameter>user_data</parameter>&#160;:</term>
<listitem><simpara>user data set when the signal handler was connected.</simpara></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
</chapter>