clean up code generation in CmpNode and fix bug #784: conflicting result types for cascaded comparisons

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rename : docs/src/tutorial/pypy.rst => docs/src/userguide/pypy.rst

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rename : docs/src/tutorial/pypy.rst => docs/src/userguide/pypy.rst

disable the 'atexit' pyregr test: it calls the registered atexit handlers which triggers the module cleanup and crashes

enable in-place compilation mode for pyximport when used from test runner (improves package compatibility)

when pyximporting a package __init__ module in place, make sure we provide __path__ at module init time to support relative imports