[Python-3000] versionadded/versionchanged in doc

[Neal Norwitz]

What do we want to do with the current versionadded/versionchanged
markups in the doc for 3k?  Should we remove all references to 1.x
changes?  all 2.x changes?  Keep them?  all of them?

Given we are trying to clean things up, I think I'd prefer to remove
all the old references to 1.x/2.x changes.  I'm not sure how to handle
any of the 3.x changes.  I expect those will be in a separate porting
doc or some such.  So my first thought is that it would be nice to
have all the doc be clean.  My only concern is that it might be
confusing for people.  Though my first guess is that it won't be any
more confusing than anything else we do, so I'd prefer to see it
cleaned up.

Thoughts?

n