reduce lifetime of exception tuple in with-statement exception exit case by making the WithExitCallNode own it instead of the exception clause

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extra : amend_source : affe6e89d8c2c49654f376fbbda3b1ad29190895

--HG--
extra : amend_source : 51a4e6ec35c70af746630fcada3982c2decde872

make sure the optimised try-finally always generates code for the original finally block subtree (just in case it references something external)

--HG--
extra : amend_source : c948151354a77be026c92d57abc151e51fb271c6

mark node position in C file when starting to generate the node's code, not that of the subexpressions

--HG--
extra : amend_source : 566ce3ed6bd0efbb075126a6c5823b773c72d2ea

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

let RemoveUnreachableCode discard any PassStatNodes (e.g. added by analysing declaration-only ExprStatNode)