python 3 port: automated changes by a slightly modified python-modernize

(replacing unicode with six.text_type, but not replacing u"" by six.u(""))
python 3 port: manual fixes, remove 2to3 from setup.py, remove fixers
_markupsafe: remove some py2.4/2.5 compat code
utils: remove some old py compat code
update docs / changelog about python requirement, add myself to AUTHORS

also added 2 FIXMEs to intro.rst about the debugsupport for python 2.4
that needs to get removed
setup.py: add "six" library to install_requires
Trash debugsupport.
Add myself.
A bit of cleanup in the environment
Add tox configuration
We don't support 2.4 anymore.
No need for tuple comparisons.
Merge pull request #212 from DasIch/add-tox

Add tox configuration
Added .tox to .gitignore
Fixed a check that broke pypy
Merge pull request #213 from Lukasa/luk-sprint-branch

Sprint: Misc fixes.
Cleanup up some imports
Correctly compare version type.
Don't assign the range type each time.
file -> open for 3.x support.  This fixes #152