prevent compile time constant folding of non-portable string comparisons (e.g. between bytes and str)

avoid risk of stale pointers by looking up Cython types module on each request (shouldn't hurt much to do it a couple of times during module initialisation)

discard useless (PyObject*) casts from values of builtin types which are PyObject* internally anyway (saves lots of C code)

--HG--
extra : amend_source : 240f49031159777036e1e6a139b6d736f59de337

fix C compiler warning when checking int overflow for division by enum values on 32 bit systems (in case anyone cares...)

minor improvements in __Pyx_ArgTypeTest() and prevent it from raising C compiler warnings by inlining it

infer type of items in tuple/list constants on indexing (especially where all items have the same type)

--HG--
extra : amend_source : 1e8bf2d512c244f48654f43e37283d800e5d961a

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