Add support for Python 3.0

[Julien ÉLIE]

Python 3.0 was released on December, 3rd 2008. The syntax currently used in Python 2.x scripts shipped with INN is not compatible with the new version. Therefore, innd and nnrpd Python filters should be reviewed and made compatible with both Python 2.x and 3.0.

Compilation with Python 3.0 API should also be checked (new functions to use? no issue when building INN with Python support?)

Also be sure that INN compiles fine with Python 2.5.x and 2.6.x.

[Julien ÉLIE]

(In [8250]) In Python samples:

• Remove tabulations for indentations (not allowed by Python 3.0 when spaces are used for that purpose).
• Add a comment for "except Exception *as* errmsg" (new syntax).
• Add a comment for memoryview() instead of buffer() which is absent from Python 3.0.
• Remove occurrences of types.InstanceType? (absent from Python 3.0).
• Use parenthesis for print().
• Add a hook to use sys.intern() instead of intern() for Python 3.0.

All the samples are for directly use with Python 2.x.
Commented lines are present wherever the syntax has
changed with Python 3.x.

see #78

[Julien ÉLIE]

(In [8252]) Add notes about buffers and memory views in documentation.
Also fix a wrong syntax to have access to a dictionary key.

see #78

[Julien ÉLIE]

Scripts are now compatible with Python 3.0. This ticket is currently only a build issue.

[Julien ÉLIE]

Also consider dropping support for Python 2.1 and before. It would allow to properly search for the python binary (in m4/python.m4) thanks to the distutils.sysconfig module which appeared in Python 2.2.
The current M4 file does not work with Python 3.

[Julien ÉLIE]

(In [9899]) Python support: use the distutils.sysconfig module at configure time

Drop support for Python 2.1 and before. It will allow to properly search
for the python binary (in m4/python.m4) thanks to the distutils.sysconfig
module which appeared in Python 2.2.0, released in December 2001!
So it is no longer an issue in 2015.

For the record, Python 1.5.2 was currently enough to build INN.

One of the issues fixed is that on several systems, the
/usr/lib/python2.7/config directory does not exist. It can for instance
be /usr/lib/python2.7/config-x86_64-linux-gnu, so the build fails because
"config" is hard-coded in the current way the detection is coded.

see #78

[Julien ÉLIE]

Milestone renamed

[Julien ÉLIE]

Fixed in commit [10276]. Tested with Python 2.7, 3.3 and 3.6.