Replacement for dtmf handling (ALways using rfc2833, old devices don't support rfc2833 so we simulate it by inserting dtmf frames into the stream).

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5527 43c1dc8c-776e-4df2-8ef1-6e829299be21
Preparing to release V4.2. Switching this version to Release Candidate 1 status

git-svn-id: https://svn.code.sf.net/p/chan-sccp-b/code/trunk@5528 43c1dc8c-776e-4df2-8ef1-6e829299be21