emit "DC_EVENT_MEMBER_ADDED" and python plugin event "member_added" for securejoin or non-securejoin additions of a contact to a chat. also fixup some docs

python/src/deltachat/__init__.py

@@ -86,4 +86,9 @@ def register_global_plugin(plugin):
     gm.check_pending()
 
 
+def unregister_global_plugin(plugin):
+    gm = hookspec.Global._get_plugin_manager()
+    gm.unregister(plugin)
+
+
 register_global_plugin(eventlogger)

python/src/deltachat/account.py

@@ -76,6 +76,10 @@ class Account(object):
         elif name == "DC_EVENT_MSG_DELIVERED":
             msg = self.get_message_by_id(ffi_event.data2)
             self._pm.hook.process_message_delivered(message=msg)
+        elif name == "DC_EVENT_MEMBER_ADDED":
+            chat = self.get_chat_by_id(ffi_event.data1)
+            contact = self.get_contact_by_id(ffi_event.data2)
+            self._pm.hook.member_added(chat=chat, contact=contact)
 
     # def __del__(self):
     #    self.shutdown()
@@ -342,6 +346,13 @@ class Account(object):
         """
         return Message.from_db(self, msg_id)
 
+    def get_contact_by_id(self, contact_id):
+        """ return Contact instance or None.
+        :param contact_id: integer id of this contact.
+        :returns: None or :class:`deltachat.contact.Contact` instance.
+        """
+        return Contact(self._dc_context, contact_id)
+
     def get_chat_by_id(self, chat_id):
         """ return Chat instance.
         :param chat_id: integer id of this chat.

python/src/deltachat/const.py

@@ -99,6 +99,7 @@ DC_EVENT_IMEX_FILE_WRITTEN = 2052
 DC_EVENT_SECUREJOIN_INVITER_PROGRESS = 2060
 DC_EVENT_SECUREJOIN_JOINER_PROGRESS = 2061
 DC_EVENT_SECUREJOIN_MEMBER_ADDED = 2062
+DC_EVENT_MEMBER_ADDED = 2063
 DC_EVENT_FILE_COPIED = 2055
 DC_EVENT_IS_OFFLINE = 2081
 DC_EVENT_GET_STRING = 2091