[O] [ANN] Changes to link syntax

[Nicolas Goaziou]

Hello,

I finally pushed changed about escape syntax in bracket links. Here is
the excerpt from ORG-NEWS:

    Org used to percent-encode sensitive characters in the URI part of the
    bracket links.

    Now, escaping mechanism uses the usual backslash character, according
    to the following rules, applied in order:

    1. All consecutive =\= characters at the end of the link must be
       escaped;
    2. Any =]= character at the very end of the link must be escaped;
    3. Any =]= character followed by either =[= or =]= must be escaped;
    4. Other =]= and =\= characters need not be escaped.

    When in doubt, use the function ~org-link-escape~ in order to turn
    a link string into its properly escaped form.

    The old ~org-link-escape~ and ~org-link-unescape~ functions have
    been renamed into ~org-link-encode~ and ~org-link-decode~.

I added a checker in "org-lint.el" to detect old percent-encoding escape
syntax in links.

Internally, I also moved all link related code from "org.el" to "ol.el",
and renamed libraries defining a new link type with "ol-" prefix. (e.g.
"org-bbdb.el" to "ol-bbdb.el"), much like "ox-" prefix.

Feedback is welcome.

Regards,

-- 
Nicolas Goaziou