Drop autogenerated files and add more .gitignore entries

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Add Call-IDs to replies

Unfortunately RTPproxy replies doesn't contain request's Call-ID which makes it
difficult to select all the packets belonging to the SIP session. So let's add
virtual field to each reply which contains Call-ID extracted from the
corresponding request.

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>