Add support for format-edn middleware & fix #977

[cichli]

I'm sure there's a better way to do cider--format-reindent. Originally I thought of indent-buffer after insertion, but that would only work for EDN.

Feedback welcome!

[bbatsov]

I'm sure there's a better way to do cider--format-reindent. Originally I thought of indent-buffer after insertion, but that would only work for EDN.

I'm definitely confused by it. :-) Will think a bit more on the subject tomorrow.

[cichli]

Basically, we know that any leading whitespace before the first char will be stripped, so start is definitely the position where the form will begin. So we just add start-column spaces to the start of every line after the first (in addition to the spaces already added by the formatting op).

[cichli]

This (along with the format-code commands) fixes #535 btw.

[bbatsov]

👍