[BUG] `org-fill-paragraph' doesn't respect formatting

[Tor Kringeland]

Applying `org-fill-paragraph' to /e.g./

  /Some text./  Some more text.

when `sentence-end-double-space' is t removes the double space to a
single space.  The same happens with other formatting like *bold* and
_underline_.  In other instances it is more context aware.  /E.g./
applying it to

  (Some text.)  Some more text.

does nothing, which is correct.