Python gaurantees that its builtin sort for mutable sequences is stable.
For more details, see note (9) in:

  * https://docs.python.org/2/library/stdtypes.html#mutable-sequence-types

I couldn't come up with a decent way to test this.

Implement the `cmp` as defined here:

* https://docs.python.org/2/library/functions.html#cmp

Implementing this builtin required implementing a fair
amount of supporting logic to do 3-way comparisons. The
3-way comparison implementation in CPython is somewhat
complex, thus there may be some cases that still need
support. This is a good start, though.

Pull values from Go syscall package.

Previously Go typedefs for simple types (e.g. `type myInt int`) would return the underlying base type (e.g. `int`) from __native__. They now correctly convert to the typedef when used in a Go context.

* Start implement string slicing
* implement unicode slicing

* Implement print_function future feature

This allows the import statement `from __future__ import print_function` to
work, by setting a flag on the parser to treat print statement/keyword as a
syntax error.

* Implemented via descriptors instead of overriding GetAttribute

* Implement os.chdir, os.getcwd.
* Implement os.path.abspath. Add _AssertEqual() to check not only values but also types.

The link was interpreted as local and did link to https://github.com/google/grumpy/blob/master/jyni.org instead of http://jyni.org

Implement the `any` as defined here:

    * https://docs.python.org/2/library/functions.html#any

Note that a new helper function `seqFindFirst` was added that
is used to implement `builtinAll`, `builtinAny`, and `seqContains`.

Implement the `all` as defined here:

* https://docs.python.org/2/library/functions.html#all

This patch finishes implementing support for unary minus.
The slot and core dispatch functions were already there,
but the individual numeric slot implementations were missing.

* Implement os.path.dirname.
* Implement os.path.exists, os.path.isdir, os.path.isfile.

Implement the `abs` as defined here:

* https://docs.python.org/2.7/library/functions.html#abs