Issue 7994: Make object.__format__ with a non-empty format string a PendingDecprecationWarning. Still need to remove uses of this from various tests.

a socket option available on FreeBSD 7.1 and newer.

* PyCObject_AsVoidPtr() can now open capsules.  This addresses
  most of the remaining backwards-compatibility concerns about
  the conversion of Python 2.7 from CObjects to capsules.
* CObjects were marked Pending Deprecation.
* Documentation about this pending deprecation was added to
  cobject.h.
* The capsule source files were added to the legacy PC build
  processes.

Also rewrite the Decimal __hash__ method so that it doesn't rely on
float('inf') being valid: float('inf') could raise an exception on
platforms not using IEEE 754 arithmetic.

Float to decimal comparison operations now return a result based on
the numeric values of the operands.  Decimal.__hash__ has also been
fixed so that Decimal and float values that compare equal have equal
hash value.

as a regular test by regrtest.py, and fails.

function declaration, which was kept for backwards compatibility reasons,
is now removed (the macro was introduced in 1997!).

allowing to use advanced gdb features when debugging Python.

check_warnings docs to be clearer.

Replace catch_warnings with check_warnings when it makes sense.  Use assertRaises context manager to simplify some tests.

references.

Fix test for xml.etree when using a non-ascii path.  And use check_warnings instead of catch_warnings.

  argument `-` which tells it to read files to compile from stdin.  Each line
  is read on demand and the named file is compiled immediately.  (Original
  patch by Piotr Ożarowski).

Thanks to Éric Araujo for noticing that.

Revert r79179 and merge r75584 to explain how to implement a queue using collection.deque instead of a list.