Support Python 3.x

[pjz]

The world is changing. We should change with it.

[chadwhitacre]

Need new mimeparse: https://pypi.python.org/pypi/mimeparse.

[pjz]

Did some work on this and ran into

...
  File "/home/pj/src/aspen-meta/aspen/aspen/http/request.py", line 144, in <module>
    class IntWithRaw(int):
TypeError: nonempty __slots__ not supported for subtype of 'int'

... which seems to me to be more impetus to, as #357 says, ' #222 or drop back to werkzeug?'

[pjz]

https://utcc.utoronto.ca/~cks/space/blog/python/IntSlotsPython3k

[chadwhitacre]

https://searx.me/?q=python%20subclass%20builtin%20types&categories=general

[pjz]

Known, wontfix bug: http://bugs.python.org/issue1173475

[chadwhitacre]

(In a sense the way to deal with this issue when porting to Python 3 is simple; you just stop using slots on your subclass of int. Everything works the same and your instances just take up a bit more memory.)

[chadwhitacre]

Refer to http://pythonhosted.org/six/. Either bring it in as a dependency, or copy/paste code from it into our own backcompat submodule.

[chadwhitacre]

Consider https://pypi.python.org/pypi/tox for testing multiple Python versions locally.

[chadwhitacre]

@Changaco Any interest in landing this before 1.0 in September?

[Changaco]

Yes, python3 is the next item in my TODO. Don't know when I'll get around to it, but it should be doable before 1.0.

[Changaco]

I have Pando's tests passing on python3. :-)

[chadwhitacre]

❗