* TLS Subject Checking in tport
  
  sofia-sip/tport.h:
  * tport_delivered_from_subjects() returns type (su_strlst_t const *)
  * Export tport_subject_search()
  
  sofia-sip/tport_tag.h + tport_tag.c:
  * Remove TPTAG_TLS_VERIFY_PEER()
    - Depreciated.  Use TPTAG_TLS_VERIFY_POLICY instead.
    - Binary Compatibility is preserved.
  * Add TPTAG_TLS_VERIFY_POLICY()
    - tport can verify incoming and/or outgoing connections, using:
      1) Certificate Signatures only - or - 
      2) Certificate Signatures and Certificate Subjects
  * Add TPTAG_TLS_VERIFY_DEPTH()
    - Restrict certificate chain verification to a set length.
  * Add TPTAG_TLS_VERIFY_DATE()
    - Disable notBefore/notAfter checking (application: embedded devices)
  * Add TPTAG_TLS_VERIFY_SUBJECTS()
    - Incoming connections must present client certificates with subjects
      that match an item in this list.
    - Intended Use: Proxy Authentication
  * Replaced TPTAG_TRUSTED() with TPTAG_X509_SUBJECT()
    - Commented out for future use.
    - Intended Use: SIP User Identities in Server Certificates.
  * Add appropriate doxygen documentation.
  
  tport.c
  * Add tport_subject_search()
    - Subject can be a hostname, IP Address, or a URI.
    - Valid subject examples include:
        example.com
        alice@example.com
        sip:alice@example.com
        sips:alice@example.com
  * tport_by_addrinfo() matches tpn_canon against the subject list
      of reusable TLS connections.
  
  tport_tls.h:
  * Add tls_init_secondary()
  * Remove tls_init_slave() & tls_init_client()
  
  tport_tls.c:
  * tls_verify_cb() supports TPTAG_TLS_VERIFY_DATE()
  * tls_post_connection_check() verifies certificate subjects.
  * tls_init_secondary()
    - Replaces tls_init_slave(), tls_init_client(), and tls_clone().
  
  tport_type_tls.c:
  * Removed erroneous reference to tport_tls_deliver()
  * Fix a memory leak caused by duplicate calls to tls_clone().
  * Populate the (tport_t *)->tp_subjects field with peer certificate data for
    new secondary connections.



git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@11830 d0543943-73ff-0310-b7d9-9358b9ac24b2