Continue numbering from any previous numbered snippet with +n, even when previous numbered snippet does not immediately precede it.
* org-mode/lisp/org-exp.el (org-export-number-lines):
Check whether number parameter (this is a numbered block!) is
non-nil as well as whether cont is nil (this numbered block should
*not* continue numbering where we left off before!) before resetting
the count to zero.
From the docs:
If you use a `+n' switch, the numbering from the previous
numbered snippet will be continued in the current one.
With this change I believe the code complies with the docs.