- Use update-alternatives for parallel-installability with Python3 version

- Update to version 1.10:
+ BACKWARDS INCOMPATIBLE Dropped support for Python 2.5. The minimum supported
Python version is now Python 2.6.
+ BACKWARDS INCOMPATIBLE Using virtualenv.py as an isolated script (i.e.
without an associated virtualenv_support directory) is no longer supported
for security reasons and will fail with an error.
+ Along with this, --never-download is now always pinned to True, and is only
being maintained in the short term for backward compatibility (Pull #412).
+ IMPORTANT Switched to the new setuptools (v0.9.7) which has been merged with
Distribute again and works for Python 2 and 3 with one codebase. The
--distribute and --setuptools options are now no-op.
+ Updated to pip 1.4.
+ Added support for PyPy3k
+ Added the option to use a version number with the -p option to get the system
copy of that Python version (Windows only)
+ Removed embedded ez_setup.py, distribute_setup.py and distribute_from_egg.py
files as part of switching to merged setuptools.
+ Fixed --relocatable to work better on Windows.
+ Fixed issue with readline on Windows.
- Spec clean:
+ Depend on setuptools instead of distribute again
+ Package README.rst
+ Build HTML documentation and install it (instead of sources)