revise way silva handles links

[Martijn Faassen]

The way Silva handles links is a bit confused right now. Mostly it works, but
you get into trouble when you try exporting using the import/export system, or
move content in various ways, etc.

Links get produced by the following pieces of code:

* Kupu (manual entry, get link reference)
* Forms editor (manual entry, get link reference)

Links get rendered by the following code:

* XMLWidgets renderer - tries to display intelligence to deal with weird
                        kind of acquisition-based links

* XSLT renderer - doesn't do anything about links, as far as I know.

What we need to do is make sure that links are handled sensibly on *input*.
Output should be save. We could, alternatively or in addition, also do some link
rationalisation during XML export.

Various different situations exist:

* exporting and importing content
* moving content folders
* moving a single content object

we need to go through them and figure out what the right thing to do (relative
links, absolute links, something else) is.

[Andy Altepeter (aaltepet)]

(issue130). It would be nice to have a smarter link renderer that appends
'/preview_html' when in preview mode. In this
way editors can navigate the entire site in public preview mode. This feature
is
important for the editors at Bethel University, as it allows them to
check the entire preview version of a publication prior to
publishing it. Needing to add '/preview_html' after clicking a link to another
silva document is rather cumbersome. Adding this is fairly trivial.
Especially if the preview_html script adds a 'preview' flag to REQUEST.

[Kit Blake (kitblake)]

Now that we have a public preview that keeps the user in the SMI, this preview mode idea would work nicely.

But the rendered links will only be in rendered content (silva xml). Links in navigation in the layout templates won't have preview_html appended unless we want to do some js after loading.

[Andy Altepeter (aaltepet)]

Observation: keeping the user in the SMI while previewing will mean that when user clicks a link in the preview content, the SMI tabs will remain at the old location. The SMI tabs (preview tab top frame) should also go to the new content's SMI tabs.

[Andy Altepeter (aaltepet)]

Observation: SilvaDocument TOC elements: with the new preview tab there are problems, see: https://bugs.launchpad.net/silva/+bug/100947/comments/22 . When the link rendering is revised, remember to address this as well (now in the 2.1 trunk TOC elements _always_ link to the public content)

[Andy Altepeter (aaltepet)]

remember to review the duplicate bug reports, as they contain further points/issues that need to be addressed.

[Sylvain Viollon (thefunny)]

The 'preview_html' doesn't exists anymore, and links are for most of them references that are properly handled on public rendering and XML import / export (and that is done only at one place, not copied all over the place).

I think this bug is no longer.