Lupa

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* fixed undefined behaviour on ``str(lua_object)`` when the object's
``__tostring()`` meta method fails

* removed redundant "error:" prefix from ``LuaError`` messages

* access to Python's ``python.builtins`` from Lua code

* more generic wrapping rules for Python objects based on supported
protocols (callable, getitem, getattr)

* new helper functions ``as_attrgetter()`` and ``as_itemgetter()`` to
specify the Python object protocol used by Lua indexing when
wrapping Python objects in Python code

* new helper functions ``python.as_attrgetter()``,
``python.as_itemgetter()`` and ``python.as_function()`` to specify
the Python object protocol used by Lua indexing of Python objects in
Lua code

* item and attribute access for Python objects from Lua code

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* fix Lua stack leak during table iteration

* fix lost Lua object reference after iteration

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* error reporting on Lua syntax errors failed to clean up the stack so
that errors could leak into the next Lua run

* Lua error messages were not properly decoded

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* much faster locking of the LuaRuntime, especially in the single
threaded case (see
http://code.activestate.com/recipes/577336-fast-re-entrant-optimistic-lock-implemented-in-cyt/)

* fixed several error handling problems when executing Python code
inside of Lua

----------------

* fixed Python special double-underscore method access on LuaObject
instances

* Lua coroutine support through dedicated wrapper classes, including
Python iteration support. In Python space, Lua coroutines behave
exactly like Python generators.

----------------

* support for returning multiple values from Lua evaluation

* ``repr()`` support for Lua objects

* ``LuaRuntime.table()`` method for creating Lua tables from Python
space

* encoding fix for ``str(LuaObject)``