Replace wfMsgReplaceArgs by RawMessage

The replace of $n params can also be done using the Message class. In
case there are no message keys, the RawMessage class is used.

Deprecated wfMsgReplaceArgs, but added no warning, because it is used in
some extensions and from deprecated functions

Change-Id: I62091b09e4490e59ed7258566e0ddf2f8ee799d2