Update docs to reflect deprecated ext format

[keyan]

Update docs so extension developers are urged to use the new import format in preparation for removing the magic .ext redirection tool. See #1135.

[untitaker]

By the time these docs will get published, the ext format will already be deprecated or even gone.

[keyan]

@untitaker Are you suggesting not making the documentation changes at all or just changing to wording to reflect that the ext format will already have been removed?

[untitaker]

Also, time to mention your migration tool? :)

BTW thanks for putting so much work into this!

[keyan]

I changed the tense and altered the wording a bit. Additionally I wrote a little about using the tool, although I was not sure if a direct reference to the location of the script in the repo was appropriate as this might change?

No problem, my pleasure to help out. Side note, is there any way to get privileges to close/re-open issues? I'd like to help clean up the issue tracker, but don't want to bother you or DasIch every time. Thanks!

[keyan]

Actually, I realize I need to add details to setup.py so users can invoke the script. I need to read more about this, I'll make a new commit when it's ready.

[untitaker]

Thanks for wanting to help... mitsuhiko can give you those permissions.

[untitaker]

Ask him on the pocoo IRC channel

[untitaker]

Blocked by #1367, but as written there, I think the redbaron dependency should be informally documented and not be coded into the setup.py

[untitaker]

I've rewritten this and ended up with #1484. Thanks for the work so far @keyan, especially for the migration tool!