-----Changes -----

New files
- channels/sip/sip.h – A new header for shared #define, enum, and struct
  definitions.
- channels/sip/include/sip_utils.h – sip util functions shared among
  the all the sip APIs
- channels/sip/include/config_parser.h – sip config-parser API
- channels/sip/config_parser.c  – Contains sip.conf parsing helper functions
  with unit tests.
- channels/sip/include/reqresp_parser.h – sip request response parser API
- channels/sip/reqresp_parser.c – Contains sip request and response parsing
  helper functions with unit tests.

New Unit Tests 
- sip_parse_uri_test
- sip_parse_host_test
- sip_parse_register_line_test

Code Refactoring
- All reusable #define, enum, and struct definitions were moved out of chan_sip.c
  into sip.h. During this process formatting changes were made to comments
  in both sip.h and chan_sip.c in order to better adhere to the coding guidelines.
- The beginnings of three new sip APIs, sip-utils.h, config-parser.h,
  reqresp-parser.h using existing chan_sip.c functions.
- parse_uri() and get_calleridname() were moved from chan_sip.c to request-parser.c
  along with unit tests for both functions.
- sip_parse_host() and sip_parse_register_line() were moved from chan_sip.c to
  config-parser.c along with unit tests for both functions.

Changes to parse_uri()
-removal of the options parameter.  It was never used and did not behave correctly.
-additional check for [?header] field. When this field was present, the transport
 type was not being set correctly.

----- Overview -----
This patch is introduced with the hope that unit tests for all our sip parsing
functions will be written soon.  chan_sip is a huge file, and with the addition of
each unit test chan_sip is going to grow larger and harder to maintain.  I'm proposing
we begin refactoring chan_sip, starting with the parsing functions.  With each parsing
function we move into a separate helper file, a unit test should accompany it.  I've 
attempted to lay down the ground work for this change by creating two new parser
helper files (config-parser.c and reqresp-parser.c) and moving all shared structs,
enums, and defines from chan_sip.c into a shared sip.h file.  We can't verify everything
in Asterisk using unit tests, but string parsing is one area where unit tests make
the most sense.  By beginning to restructure the code in this way, chan_sip not only
becomes less bloated, but Asterisk as a whole will become more stable.


Review: https://reviewboard.asterisk.org/r/477/



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@244597 65c4cc65-6c06-0410-ace0-fbb531ad65f3