I broke test_mixin2to3 somehow; distutils2-default is okay and packaging too,
so I don?t see an obvious reason right now, I?ll investigate later.

This method was named reinitialize_command in distutils and accompanied
by a comment suggesting to change it to get_reinitialized_command.
Following that, I did the change for distutils2, but it proved
confusing: The Distribution object has an internal cache of command
objects, to make sure only one instance is ever used, and the name
get_reinitialized_command could suggest that the object returned was
independent of that cache, which it was not.  I?m reverting the name
change to make code clearer.

All code (util.byte_compile, build_py, install_lib) can now create .pyc
and/or.pyo files according to options given by users, without
interference from the calling Python?s own optimize mode or from the
sys.dont_write_bytecode switch.

The rationale is that packaging gives control over the creation of
.pyc/.pyo files to the user with its own explicit option, and the
behavior should not be changed if the calling Python happens to run with
-B or -O for whatever reason.

This is actually a bug fix, not an improvement: Digging into the early
history of distutils shows that the original author wanted this behavior
(see for example comments in build_py in r12940).

This codebase is compatible with 3.1, 3.2 and 3.3.  It was converted with 2to3
and a semi-automated diff/merge with packaging in 3.3 to fix some idioms.
We?ve now come full circle from 2.x to 3.x to 2.x to 3.x again :)

Starting from now, contributors can make patches for packaging (preferred, as
the stdlib?s regrtest is very useful), distutils2 or distutils-python3, and
we?ll make patches flow between versions.

shutil, sysconfig, tarfile and their tests have been updated to the
latest 3.2 version (except for test_tarfile which is not backported yet)
and edited to be compatible with 2.4.

Duplicates added in util during the Great Update have been deleted, as
well as functions I removed recently in packaging.  Unneeded modules in
_backport have been deleted or moved to d2.compat.

Backports:
- sysconfig is now always imported from our backports
- when hashlib is not found, our backport is used instead of the md5
  module (debatable; we could just drop hashlib)

Version-dependent features:
- PEP 370 features are only enabled for 2.6+
- the check for sys.dont_write_bytecode was fixed to use getattr
  with a default value instead of hasattr

Idioms/syntax:
- octal literals lost their extra 0
- misused try/except blocks have been changed back to try/finally
  (it?s legal in 2.4 too, it?s only try/except/finally that isn?t)
- exception catching uses the regular 2.x idiom instead of sys.exc_info
- file objects are closed within finally blocks (this causes much
  whitespace changes but actually makes diff with packaging easier)

Renamed modules:
- some missed renamings (_thread, Queue, isAlive, urllib.urlsplit, etc.)
  were fixed

Other:
- a few false positive replacements of ?packaging? by ?distutils2? in
  comments or docstrings were reverted
- util.is_packaging regained its name
- assorted whitespace/comment/import changes to match packaging