Sqlalchemy tests2

We would keep on adding the same object to the weakrefs list,
which would eventually trigger a collection, and cause all sorts
of weird things to happen.

This isn't just a performance optimization, but is actually important
since people put things in dicts that don't __eq__ themselves.
The common example (and test here) is NaN, but in particular sqlalchemy
does this with clauses (where __eq__ returns a new sql clause).

Also, handle cases that __eq__ returns non-bool

And add set.difference_update() and set.isdisjoint()

Using their test runner is quite hard since it tries to override a lot
of basic functionality (ex for enhanced tracebacks).  So just do some
manual test discovery, and only run the tests that cpython can pass
using this setup.

We still fail a couple more though.

Clean up the BoxedTuple class

Fix "sys.excepthook is missing" warnings

Add more imp.* functions, set correct module.__file__, import * with non module globals

Get `cpython/test_property.py` to pass

by adding sys.excepthook.

Add pyxl hello world integration test

Add support for weakref.proxy

add imp.is_builtin, imp.is_frozen, imp.new_module, support object.__hash__(arg), don't always set module.__file__

Add support for specifying the encoding inside source files.

Support for inspect.isgenerator, round(int), property.__doc__

Sqlalchemy tests

Apparently the 'assert' statement works by looking up the "AssertionError"
name in the global scope, and then raising an exception of that type.

pytest uses this to override assertion behavior.

By replacing the entry in sys.modules.  pytest does this.

This was preventing subclasses of module from overriding __init__.
Yes, that really happens.

sqlalchemy uses pytest to run its test suite, which unfortunately
has been hard to get working.

I had to change 'new_weakref' to use 'tp_alloc' instead of 'PyObject_GC_New'
in order to create a weak ref because 'PyObject_GC_New' allocated memory
is scanned conservatively.
'tp_alloc' points to 'PystonType_GenericAlloc' and is of PYTHON type.

Ignore generated tmp folders.

visit im_class in gc handler

-m support