Be sure to clean up in the right order when unloading

We should only free the userstate after all the pidgin stuff is cleaned
up, as some of it may use the context.  Indeed, this fixes a crash bug
when you try to unload the OTR module while a SMP session is in
progress.

The right thing to do is to deallocate things in the reverse order that
you allocated them, which is what we do now.

otr-plugin.c

@@ -107,7 +107,7 @@ OtrlUserState otrg_plugin_userstate = NULL;
 
 /* GLib HashTable for storing the maximum message size for various
  * protocols. */
-GHashTable* mms_table;
+GHashTable* mms_table = NULL;
 
 
 /* Send an IM from the given account to the given recipient.  Display an
@@ -1160,6 +1160,7 @@ static void otrg_init_mms_table()
 static void otrg_free_mms_table()
 {
     g_hash_table_destroy(mms_table);
+    mms_table = NULL;
 }
 
 static gboolean otr_plugin_load(PurplePlugin *handle)
@@ -1301,10 +1302,11 @@ static gboolean otr_plugin_unload(PurplePlugin *handle)
     void *core_handle = purple_get_core();
 
     /* Clean up all of our state. */
-    otrl_userstate_free(otrg_plugin_userstate);
-    otrg_plugin_userstate = NULL;
 
-    otrg_free_mms_table();
+    purple_conversation_foreach(otrg_dialog_remove_conv);
+
+    otrg_dialog_cleanup();
+    otrg_ui_cleanup();
 
     purple_signal_disconnect(core_handle, "quitting", otrg_plugin_handle,
 	    PURPLE_CALLBACK(process_quitting));
@@ -1325,10 +1327,10 @@ static gboolean otr_plugin_unload(PurplePlugin *handle)
     purple_signal_disconnect(blist_handle, "blist-node-extended-menu",
 	    otrg_plugin_handle, PURPLE_CALLBACK(supply_extended_menu));
 
-    purple_conversation_foreach(otrg_dialog_remove_conv);
+    otrl_userstate_free(otrg_plugin_userstate);
+    otrg_plugin_userstate = NULL;
 
-    otrg_dialog_cleanup();
-    otrg_ui_cleanup();
+    otrg_free_mms_table();
 
     return 1;
 }