walk js prototype chain to retrieve native ptr

Conflicts:
	examples/basic.js
	lib/cpgf/src/scriptbind/gv8bind.cpp
Merge branch 'develop' into hotfix/js-subclassing

Conflicts:
	src/scriptbind/gv8bind.cpp
Merge pull request #7 from cpgf/hotfix/js-subclassing

walk js prototype chain to retrieve native ptr