MIscellaneous fixes

[ming]

This is a placeholder for minor/miscellaneous fixes on this milestone.

[ming]

(In [3317]) Re #1134: for iOS4, remove unnecessary wrapping of sockets during creation.

[nanang]

(In [3318]) Misc (re #1134): fixed default value of pjsua app param "--snd-auto-close" in pjsua app help message (was -1, should be 1, see r2493).

[bennylp]

(In [3319]) Misc (re #1134): fixed error in Makefile target for generating doxygen documentation when WWWDIR is specified

[bennylp]

(In [3320]) Misc (re #1134): fixed wrong OpenBSD thread priority max value (thanks David Coppa for the report)

[bennylp]

(In [3327]) Re #1134 (misc fixes): fixed various doxygen warnings, as well as added overview section in pjmedia documentation

[bennylp]

(In [3331]) Misc (re #1134): added Supported header in outgoing SUBSCRIBE request. Although RFC 3265 says it is only optional, some downstream RFC may bring this requirement to SHOULD strength - e.g. RFC 5373 (thanks Johan Lantz for the suggestion)

[ming]

(In [3335]) Misc (re #1134): Fixed memory leak after getting audio route capability in coreaudio_dev

[bennylp]

(In [3341]) Misc (Re #1134): do not allow subscription state callback to be called with NULL event parameter as application may not expect this

[bennylp]

(In [3343]) Misc (re #1134): added the missing ARCH environment variable in CPP command in configure-iphone script (thanks MrGecko? for the patch)

[bennylp]

(In [3344]) Misc (re #1134): fixed failure in resolving DNS A resolution if the answer contains more than one CNAME redirection before an A record is found (thanks Régis Montoya for the report)

[bennylp]

(In [3345]) Misc (re #1134): changed dynamic payload type starting value for internal codecs to 96 (from 101) as we are running out of constants. Also added more comments to clarify the restriction on the value, i.e. it must be less than 128 (thanks Robbie Hanson for the suggestion)

[bennylp]

(In [3346]) Misc (re #1134): fixed failed unit tests due to changes in DNS resolver code in r3344

[bennylp]

(In [3350]) Misc (re #1134): enable doxygen documentation for pj_actievsock_set_iphone_os_bg()

[bennylp]

(In [3351]) Misc (re #1134): added the ability to add python module build with the top level build, by adding pjsip-apps/src/python into EXTRA_DIRS in user.mak. Also changed the make command in python module to just build the module without installing since installing needs root permission

[bennylp]

(In [3352]) Misc (re #1134): fixed compilation error in python module due to last change in session timer field from require_timer to use_timer. Thanks Beau Gunderson for the patch!