Make the patch for master branch, 4.0 doesn't take any new feature and I applied the patches to master branch anyhow.

Also, do not forget the patch for xml documentation.

Cheers,
Daniel

Patch for master branch is in the attachment.

Changelog:
- documentation is updated
- tcpconn_id initialized to "-1" for contacts loaded from a database during startup (Write-Back & Write-Through database modes).
- tcpconn_id is being updated when UA reconnects and refreshes its registration.