Use `create()` rather than `_create()`

[corranwebster]

This carries out the next two steps of #729

• [x] replaces calls to _create with calls to create
• [x] that classes migrate the implementation of _create into create, and make _create call create

as well as the next step in removing create calls from __init__ methods:

• [x] properly deprecate auto-create, but don't fail yet; push toward removing create keyword argument.

[corranwebster]

This PR seems to include a couple of .zip files that I think shouldn't be there. (cf: #776)

That's what I get for doing git commit -a after a search and replace :(

[mdickinson]

Yes, sorry - I take it back about the .zip files. I thought they were new files, but they're modifications to existing files.