Fixed uncommenting line "spilling" to next line

When there are adjacent lines to be uncommented, e.g.

    ;; foo
    ;; bar

and foo is uncommented using `evilnc-hotkey-comment-operator`, bar would also be uncommented.  The most likely explanation is that `end` passed in `(evilnc--extend-to-whole-comment beg end)` is on the next line.

Avoided this case by avoiding `evilnc--extend-to-whole-comment` when commenting/uncommenting lines.