SwitchTransform is unable to detect all cases of duplicate values, which
result in errors at compile time in the generated code.

--HG--
extra : amend_source : 7954c320c39d51cde9ac7d4368258ceb56a3bc2f

--HG--
extra : amend_source : 2797e0ad678cc0a33a2548a8a20b00475bc8a21b

Conflicts:
	CHANGES.rst

--HG--
extra : amend_source : 2797e0ad678cc0a33a2548a8a20b00475bc8a21b

revert dynamic tp_new() override because it breaks instantiating types with arguments that object.__new__()/object.__init__() don't expect

reuse object's tp_new() for simple extension types if possible to improve support for multiple inheritance

--HG--
extra : amend_source : f3b7f004f905c791e6ced2a5b27fffa21f9ceb08

undo the Python-optimisationism of assigning bound/unbound methods to local variables when Cython can call a builtin C function instead

--HG--
extra : amend_source : 121eadd540f25f9e43f6e6b60853eeab18d11620

--HG--
extra : amend_source : 6fe9294d38a26b208899453b4a12739dcc496c16