Add crux-with-region-or-sexp-or-line

[deejayem]

Similar to the existing macros such as crux-with-region-or-line, add a new macro called crux-with-region-or-sexp-or-line, which advises a command so that if it is called with no active region, it is instead called on the current sexp (or string), falling back to the current line.

Note: I found that some of the functions that might been more obvious to use for this didn't work correctly, e.g. list-at-point doesn't work with Clojure vectors and sets (but (thing-at-point 'list) handles them fine), and beginning-of-sexp/thing-at-point--beginning-of-sexp move along a single symbol, but not to the beginning of the list.

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Thanks!

[bbatsov]

Looks useful. Thanks!