org.el (org-mode): Set `paragraph-start'

org.el (org-mode): Set `paragraph-start'

* org.el (org-mode): Set `paragraph-start'.

The value inherited from outline-mode is wrong because
outline mode does not enforce the space after the star
while Org-mode does.

outline-mode value for `paragraph-start' prevents filling
paragraphs containing a string like " -- *bold*": in this
case, fill-paragraph might think that the "*b" part of the
string starts a paragraph while it does not.

Thanks to Samuel Wales for reporting this.