Changelog:
- The reference count displayed by sip.dump() now has the same caveat as sys.getrefcount().
- Added SIP_NULLPTR to the public API.
- Added support for size_t.
- Added sipLong_AsSizeT() to the C API.
- Added the '=' format characters to sipBuildResult() and sipParseResult().
- Bug fixes.
Fixes T7647
Signed-off-by: Pierre-Yves <pyu@riseup.net>