[Numpy-discussion] Numpy deprecation schedule

[Nathaniel Smith]

A number of items on the 1.8 todo list are reminders to remove things
that we deprecated in 1.7, and said we would remove in 1.8, e.g.:
  https://github.com/numpy/numpy/issues/596
  https://github.com/numpy/numpy/issues/294

But, since 1.8 is so soon after 1.7, we probably shouldn't actually do that.

I suggest we switch to a time-based deprecation schedule, where
instead of saying "this will be removed in N releases" we say "this
will be removed in the first release on or after (now+N months)".

I also suggest that we set N=12, because it's a round number, it
roughly matches numpy's historical release cycle, and because AFAICT
that's the number that python itself uses for core and stdlib
deprecations.

Thoughts?
-n