extended test case: test that common method forwarding patterns still work with the new special method setup code

extended test case: test that common method forwarding patterns still work with the new special method setup code

Fix #561 doctests to work under Python 2 and 3; remove problematic doctest from type_slots_int_long_T287.pyx

--HG--
rename : tests/compile/tryexcept.pyx => tests/run/tryexcept.pyx

--HG--
rename : tests/run/special_methods_T561.pyx => tests/run/special_methods_doctests_T561.pyx

This is cleaner and has consistancy with how we handle removed PyInt* stuff.

--HG--
extra : rebase_source : 19ae472e99657b62b6730af74254345cf38d62a4

Fix #566, where __getslice__ generates code that gives a confusing compiler error under Python 3.  (Now you get a Cython compiler warning and a direct error message.)  A modification of the patch for #215.