Fixed uncommenting line "spilling" to next line

When there are two 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.
Merge pull request #24 from untf/master

Fixed uncommenting line "spilling" to next line
doc updated v1.2.9