[ADD/WIP] Two-way replies

Call me Seija Kijin the way I apply my Reverse Ideology.

src/Events.c

@@ -192,3 +192,14 @@ MatrixCreateReact(char *event, char *body)
     return map;
 
 }
+void
+MatrixSetReply(HashMap *map, char *event)
+{
+    if (!map || !event)
+    {
+        return;
+    }
+    JsonValueFree(JsonSet(map, JsonValueString(event),
+        3, "m.relates_to", "m.in_reply_to", "event_id"
+    ));
+}