Add cider-clojurec-eval-destination custom variable

[garrett-hopper]

Adds a cider-clojurec-repl-type-override variable to allow overriding the default behavior of sending CLJC evals to both CLJ and CLJS.

Also includes a cider-set-clojurec-repl-type-override function to prompt the user to set this variable local to the buffer

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Thanks!

If you're just starting out to hack on CIDER you might find this section of its
manual extremely useful.

[vemv]

Thanks much!

I mainly suggested removing the nil choice which can simplify things.

Cheers - V

[bbatsov]

The new defcustom should also be mentioned in the user manual.

[garrett-hopper]

The new defcustom should also be mentioned in the user manual.

Where should this be added exactly?
https://github.com/clojure-emacs/cider/edit/master/doc/modules/ROOT/pages/basics/clojurescript.adoc seems to not exist on master.

[bbatsov]

Apart from my small remarks the changes look good. You might also want to squash those commits together.

[garrett-hopper]

Commits squashed 🙂

[vemv]

One last thing and it's in 👍