Follows Python behaviour, but excludes "__pyx_…" names in utility code.

Closes GH-1382.

Currently excludes PyPy2.
Closes GH-2781.

Add "tp_pypy_flags" field to PyTypeObject struct when compiling in PyPy 6.0+ in order to avoid C compiler warnings about an uninitialised struct field.

Right now it's used in a few simple cases (function call and single assignment)
Don't attempt to remove reference types.
Be wary of the "safety check" for double moves when things like result() are called twice
Made sure fallback option was genuinely c++03 complient so that test should pass on clang

This reverts commit 52635828.

multiprocessing requires some additional setup on Windows, which I don't currently want to implement in setup.py.

Fixes GH-3534.

Fixes GH-3534.

Suppress non-error output of the C compiler in test runner unless there is a test failure or at least some error output as well.

Fixes #3531.

Fixes #3531.

Closes #2753.

* Potential fix for GH issue #3203

Gets the specialized type if possible from
NameNode.analyse_as_type

This does introduce a potential new bug:
```
cimport cython

just_float = cython.fused_type(float)

cdef OK1(just_float x):
    return just_float in floating

cdef fail1(just_float x, floating y):
    return just_float in floating

cdef fail2(floating x):
    return floating in floating

def show():
    """
    >>> show()
    True
    True
    True
    True
    """
    print(OK1(1.0))
    print(fail1(1.0, 2.0))
    print(fail1[float, double](1.0, 2.0))
    print(fail2[float](1.0))
```
fail1 and fail2 work before this patch but fail with it. It isn't
clear to me if this should actually be considered a bug. It
works in both versions with `cython.floating`, which possibly
suggests analyse_as_type in AttributeNode should also be changed

* Bring attribute.fused types in line

* Removed try-catch

* Fix and test "type in fused_type" special-case

* Added "analyse_as_specialized_type"

* Fixed cpp_operators (handle type is None)

Make CodeWriter inherit from ExpressionWriter in order to support all kinds of expressions without duplicating code. (GH-3528)