Pass group matches for regex matches in react_room_messages

mytrix.py

@@ -136,7 +136,10 @@ class Matrix:
 
         The cases argument takes a dictionary mapping strings or compiled regexs to callables.
         All received messages are compared to the keys, and on match, the respective callable
-        is called. The callback is passed the matching message as only argument.
+        is called.
+
+        The callback is passed the matching message for string matches, or the list of matched
+        groups for regex matches.
 
         The get_room_messages method is called with default values, resulting in this method always
         reacting to new messages since its last call.
@@ -155,9 +158,10 @@ class Matrix:
                             matches.append(message)
                             func(message)
                     elif isinstance(key_, re.Pattern):
-                        if key_.match(message):
+                        finds = key_.findall(messaage)
+                        if finds:
                             matches.append(message)
-                            func(message)
+                            func(finds)
 
         return matches