improve type inference for string %/+/* operations and use more direct C-API calls for these unicode operations

--HG--
extra : amend_source : 6fe9294d38a26b208899453b4a12739dcc496c16

get rid of 'yellow last line' problem by assigning the function exit error handling and default value return code to the signature line instead of the last code line

disable autotestdict when testing under Py3.4 and adapt autotestdict tests to make up for its smarter docstring lookup

--HG--
extra : amend_source : a382ac055ce79771e0457bed2e3b8d253581a54f

let += and -= inplace operators use pointer arithmetic when used on C strings (instead of currently failing attempt at string concatenation)

--HG--
rename : tests/broken/inplace_lhs.pyx => tests/compile/inplace_lhs.pyx
rename : tests/broken/inplace_ops.pyx => tests/compile/inplace_ops.pyx

--HG--
rename : tests/broken/voidstarcast.pyx => tests/run/voidstarcast.pyx

--HG--
rename : tests/broken/typeofexttype.pyx => tests/run/typeofexttype.pyx