fix memory leak for memory views in extension subtypes
Fix self arg type when adding optional arguments in an override.
fix typo in docs

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extra : rebase_source : 4cc5a2b5b9044e06fca82d216aa5a3c919abf033
minor doc clarification
Silent clang -Wconversion warnings
Fix bad macro CPYTHON_COMPILING_IN_PYPY -> CYTHON_COMPILING_IN_PYPY
improve error handling in __Pyx_init_sys_getdefaultencoding_params()

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extra : transplant_source : %CD%DB%8CT%85r%FF%0B%1C%60%B3%CD%F8%16%D8%E3%EC%C7%0BL
fix ASCII compatibility check in __Pyx_init_sys_getdefaultencoding_params(): strncmp() stops at first NUL byte which is the first byte in this case (i.e. no comparison is done at all)

--HG--
extra : transplant_source : A%2B%5BO%82%05%F7%DEm/%8Ao%08%121%96%8Ao%AB%8C
handle malloc() failure in encoding setup code

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extra : transplant_source : %F3%9A%B7r%F7%DB%C7%88%2B%D2%A4%9C%5E%0FT%B8_XS%D2
minor code cleanup

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extra : transplant_source : M%D5%2C%C2%15%9E%3C%BC%3C%89%25n%95%DF%5C%B8%B5%C5%B8%D9
make encoding setup code safer by not expecting sys.getdefaultencoding() to safely return a bytes object

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extra : transplant_source : cZx%3E%03l%AC%EDK%E3%C2%F2%2C%9BV%E5%EC%5D%B7%C8
free sys module reference earlier in encoding setup code

--HG--
extra : transplant_source : %CA%BB%21%89%8CQ%A0F%3EN%E5%7Cs%01%5D%060A%C8%AF
PyPy: Release 2.3 do exposes Py_OptimizeFlag in the C API
fix access to attributes of optimised builtin methods (e.g. '__name__')
merge 0.20.x branch into master