to return different information than the _sys_version() output
used in previous Python versions.

This also fixes issue5561: platform.python_version_tuple returns tuple of ints, should be strings

Added more tests for the various platform functions.

It seems my love of PEP 8 overrode the need for consistentcy

patch by myself #1034053

untrackable objects are not tracked by the garbage collector. This can
reduce the size of collections and therefore the garbage collection overhead
on long-running programs, depending on their particular use of datatypes.

(trivia: this makes the "binary_trees" benchmark from the Computer Language
Shootout 40% faster)

The basic algorithm remains the same; the most significant speedups
come from the following three changes:

  (1) normalize by shifting instead of multiplying and dividing
  (2) the old algorithm usually did an unnecessary extra iteration of
      the outer loop; remove this.  As a special case, this means that
      long divisions with a single-digit result run twice as fast as
      before.
  (3) make inner loop much tighter.

Various benchmarks show speedups of between 50% and 150% for long
integer divisions and modulo operations.

Make links clearer by using a Link object
instead of a list.  Use proxy links to avoid
circular references.

forever on incomplete input. That caused tarfile.open() to hang when used
with mode 'r' or 'r:bz2' and a fileobj argument that contained no data or
partial bzip2 compressed data.

integer types T, not just those for which "unsigned T" is legal.

Backport of r70459.

* Re-order methods so that those touching the underlying data
  structure come first and the derived methods come last.