* ivy.el (ivy-read): All args but PROMPT and COLLECTION are now keys.
The existing basic calls to `ivy-read' should still work, the others
need to be updated. It's best to try to use `ivy-completing-read' if
possible, since it conforms to the `completing-read' arguments.
New arguments: REQUIRE-MATCH and HISTORY. If HISTORY is nil, `ivy-history'
is used.
(ivy--sorted-files): Don't try to extend the collection.
(ivy-completing-read): Update.
* swiper.el (swiper--ivy): Update.
* counsel.el (counsel-describe-symbol-history): New defvar.
(counsel-describe-variable): Update the call, require match, use
`counsel-describe-symbol-history'.
(counsel-describe-function): Update the call, require match, use
`counsel-describe-symbol-history'.
* ivy-test.el: Update tests, since zero and one length input doesn't
return immediately any more.