Implements missing extend* tests and examples
implements Examples/perl5/callback
remove unused new defines and bring back SWIG_SHADOW define
sync up Examples/perl5/check.list
document custom SWIG_ConvertPtr() SWIG_POINTER_PERLMG flag; remove SWIG_POINTER_WR flag.
Merge branch 'talby-perl5-improvements' of ssh://github.com/swig/swig into talby-perl5-improvements