Travis-CI: Setup macOS builds

Use complete IPython dependency path in test runner to work around current test failures under appveyor.

Closes #1930.

Simplify preprocessor code that avoids the "fallthrough" C compiler warnings, assuming that "__has_attribute()" is widely supported these days. At least GCC 5.x and clang seem to have it.
Closes #1930.

Closes #1930.

Fix the first argument special method signatures of "__eq__", "__lt__" and the other richcmp methods to be of "self" type, in accordance with to the CPython specs.
See https://docs.python.org/3/reference/datamodel.html#emulating-container-types
Closes #1935.

Remove overambitious constant folding of comprehensions when they occur in a boolean context. Never assume that they are empty, since the iteration might already have required side-effects.
Closes #1920.

Closes #1916.

Considered to make it a warning, but CPython's forgiving behaviour seems unhelpful.  Can still make it a warning later.
Closed #1905.

Fix compiler crash when analysing a complex name as a type using sizeof(X) translation. Requires type analysis before the "arg_type" is set.
Closes #1908.

Prevent config lookup of "C line in traceback" option from clearing the live exception and calling setattr() with a live exception set.
Closes #1907.

Closes #1906.

Disable "numpy_parallel" test on Windows as it seems to fail based on the MSVC version (seen on appveyor).

Exclude Py3.3 from appveyor builds as it is out of maintenance anyway and isn't really supported by external packages anymore.