Add new headers

Author: link2xt

src/headerdef.rs

@@ -65,6 +65,13 @@ pub enum HeaderDef {
     ChatGroupMemberAdded,
     ChatContent,
 
+    /// Past members of the group.
+    ChatGroupPastMembers,
+
+    /// Space-separated timestamps of member addition (for current members)
+    /// or removal (for past members).
+    ChatGroupTimestamps,
+
     /// Duration of the attached media file.
     ChatDuration,