Make ivy--regex work with "[^ ]"

Make ivy--regex work with "[^ ]"

* ivy.el (ivy--split): Add a work around to not consider spaces like
"[^ ]". It's pretty hacky, the space has to come right after "[^".
But better than nothing.

* ivy-test.el (ivy--split): Add test.

Use-case: open a freedict file, where each word being defined is with no
indentation and the explanation is with indentation.

`swiper' or `counsel-grep' will now work properly with input "^[^ ]".