Comment added about a Python 2.6+ syntax (for when Python 2.5 compatibility is dropped).
Merge branch 'release' into release_python2.3

Conflicts:
	uncertainties/__init__.py
Merge branch 'master' into release
Merge branch 'master_python2.3' into release_python2.3
Merge branch 'release' into release_python2.3
Simpler output.
Merge branch 'release_python2.3' into master_python2.3
Merge branch 'release' into release_python2.3
Merge branch 'release_python2.3' into master_python2.3