Windows fixing needs help

--HG--
rename : tests/bugs/bad_c_struct_T252.pyx => tests/compile/bad_c_struct_T252.pyx
rename : tests/bugs/pxd_override_T230.pxd => tests/compile/pxd_override_T230.pxd
rename : tests/bugs/pxd_override_T230.py => tests/compile/pxd_override_T230.py
rename : tests/bugs/missing_baseclass_in_predecl_T262.pyx => tests/errors/missing_baseclass_in_predecl_T262.pyx
rename : tests/bugs/return_outside_function_T135.pyx => tests/errors/return_outside_function_T135.pyx
rename : tests/bugs/builtin_types_none_T166.pyx => tests/run/builtin_types_none_T166.pyx
rename : tests/bugs/char_constants_T99.pyx => tests/run/char_constants_T99.pyx
rename : tests/bugs/class_attribute_init_values_T18.pyx => tests/run/class_attribute_init_values_T18.pyx
rename : tests/bugs/ext_instance_type_T232.pyx => tests/run/ext_instance_type_T232.pyx
rename : tests/bugs/funcexc_iter_T228.pyx => tests/run/funcexc_iter_T228.pyx
rename : tests/bugs/ifelseexpr_T267.pyx => tests/run/ifelseexpr_T267.pyx
rename : tests/bugs/large_consts_T237.pyx => tests/run/large_consts_T237.pyx
rename : tests/bugs/methodmangling_T5.pyx => tests/run/methodmangling_T5.pyx
rename : tests/bugs/numpy_ValueError_T172.pyx => tests/run/numpy_ValueError_T172.pyx
rename : tests/bugs/unsignedbehaviour_T184.pyx => tests/run/unsignedbehaviour_T184.pyx

--HG--
rename : tests/bugs/weakref_T276.pyx => tests/compile/weakref_T276.pyx
rename : tests/bugs/c_int_types_T255.pyx => tests/run/c_int_types_T255.pyx

--HG--
rename : tests/compile/bad_c_struct_T252.pyx => tests/bugs/bad_c_struct_T252.pyx

- fix broken compile with MSVC (does not like preprocessor #if/#else/#endif inside call to macro PyRun_String)
- enable "exectest" testcase for Python 3