Change url for Help online

When the localhelp is not installed, the help is currently
served by wikihelp http://help.libreoffice.org

This patch makes the help pages to be served by
http://helponline.libreoffice.org/index.html? + params

index.html parses the params and opens the right help page.

Params passed are
- module (swriter,scalc,...) detected just after /text/
- HelpID is converted to valid url by bookmark2file.js
- valid url is rebuild then and new contents opens on _self.

Notes:
* once in the website, navigation does not come back to index.html
* index.html also redirect if visitor comes from elswhere

Change-Id: Iab0797f64024900f906c8127d275de706ba35942
Reviewed-on: https://gerrit.libreoffice.org/39264Reviewed-by: Jan Holesovsky <kendy@collabora.com>
Tested-by: Jan Holesovsky <kendy@collabora.com>

sfx2/source/appl/sfxhelp.cxx

@@ -530,7 +530,8 @@ static bool impl_showOnlineHelp( const OUString& rURL )
     if ( rURL.getLength() <= aInternal.getLength() || !rURL.startsWith(aInternal) )
         return false;
 
-    OUString aHelpLink( "http://help.libreoffice.org/"  );
+    OUString aHelpLink( "http://helponline.libreoffice.org/index.html?"  );
+
     aHelpLink += rURL.copy( aInternal.getLength() );
     aHelpLink = aHelpLink.replaceAll("%2F","/");
     try