Fix memory leakage in python bindings

The python bindings generated by the groovy code generator contain a reference counting bug which results in a memory leak whenever a std::vector is converted to a python list.  The following member functions are affected:

* xbmcvfs.listdir
* xbmc.Player.getAvailableSubtitleStreams
* xbmc.Player.getAvailableAudioStreams
* xbmcgui.Control.getPosition
* xbmcgui.Dialog.browse
* xbmcgui.Dialog.browseMultiple

The reference counting bug occurs because PyList_Append() increments the reference count of the item, so the caller needs to call Py_DECREF() because it no longer owns the object.

This bug is especially problematic when running the Watchdog Service Addon since it may result in frequent calls to xbmcvfs.listdir, and each call can leak many kilobytes of data when listing directories containing many files.
Use NULL from cstddef

This fixes build when GIT_REV is not defined.
Correctly use JAVA_HOME when generating SWIG bindings

Fix some compilation problems on windows with multiple java install or java not in path but with a correct JAVA_HOME defined
[pvr] change misleading log message

We're playing a recording, the old message made it sound like we're 
beginning to record something
[pvr] remove superfluous and and non-working log message

tag.m_strFile is always empty here anyway, and the only place where this 
method is called from already logs the event properly
[pvr] correct class name used in log message
json-rpc: make logging of incoming requests optional
json-rpc: reduce log level of potential error to warning
Merge pull request #4387 from Tolriq/swig_javahome

Correctly use JAVA_HOME when generating SWIG bindings
Merge pull request #4360 from rbalint/debian-build-fixes

Use NULL from cstddef
Merge pull request #4290 from dgburr/fix-swig-memory-leak-master

Fix memory leakage in python bindings
[osxsink/iossink] - don't spam the log with audiobuffer underruns with 0 bytes available - those underruns happen alot when we idle but sink isn't suspended yet - instead only log those underruns once until there was some data played again
Merge pull request #4400 from Jalle19/fix-log-messages

Fix some erroneous log messages
Merge pull request #4428 from Montellese/jsonrpc_optional_logging

JSON-RPC: make logging of incoming requests optional and configurable
Merge pull request #4423 from Memphiz/darwinsinklogging

[osxsink/iossink] - don't spam the log with audiobuffer underruns with 0...
[addons] ensure we clear the disabled cache when deiniting. fixes #14970
[infomanager] videoplayer.content(movies) would return true if streamdetails had been read for files outside the library. fixes #14963
Optimized CApplication::CheckShutdown() not to do further checks for timer reset conditions once resetTimer is true.
Merge pull request #4372 from ksooo/optimize_capplication_checkshutdown

Optimized CApplication::CheckShutdown() not to do further checks for tim...
add logmsg when enable changed