Remove ref to self in Lua method calls to Python bound methods.

--HG--
extra : transplant_source : %08%AF%9A%D5%B0%B2h%FD%BDa%B7%A4p%F7%5E%5E%AD%87%C9%B5
avoid redundant tuple repacking overhead for methods calls by simply unpacking the method object if self is already passed as first argument
extend tests with some more bound method calls
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