* Backports ensurepip to the 2.7 branch
* Backports some of the improved documentation to the 2.7 branch.
* Adds a private backport of the 3.x mock library as test._mock_backport
to enable saner testing of ensurepip.
Key Differences from 3.x:
* Ensurepip does not have any Makefile integration, specifically
it is not ran by default in the Makefile.
* There is no venv module in 2.7, so downstream distributors can
completely disable ensurepip, ideally with a message redirecting
to the correct way to install pip.
* To match the ``python`` command in 2.7, ensurepip will install
the unversioned ``pip`` command as well.
* No-op and hide --default-pip and add --no-default-pip to restore
the 3.x behavor on 2.7.
Fix build_tkinter.py.
Update msi.py to use environment vars and correct tcl/tk paths.
Update msilib.py to generate short names for files with multiple dots in the name.
* Now the source encoding declaration on the second line isn't effective if
the first line contains anything except a comment. This affects compile(),
eval() and exec() too.
* IDLE now ignores the source encoding declaration on the second line if the
first line contains anything except a comment.
* 2to3 and the findnocoding.py script now ignore the source encoding
declaration on the second line if the first line contains anything except
a comment.
