Changes in Engage Trunk

[Antranig Basman]

Trunk now includes a working demonstration of nested rendered components 
from the server-side - in particular an instance of the Guestbook 
(comments) app within the Exhibition view - please consult 
guestbookSpouts.js and exhibitionView.js for details of how this is 
being done. This strategy should be sufficient to get us through to the 
pilot but is as you can see too crude to be helpful in the longer term.

In particular, "makeGuestbookOptions" within exhibitionView.js uses two 
new utilities, expandMountRelative and fetchTemplateSection to derive 
the text for a template which is sent down to the nested subcomponent 
options for the guestbook directly as a string - this might well be the 
most performant and stable option. Note that for speed (of development, 
as well as execution), the "template proper" section of the template is 
delimited by a special comment format.

Two more areas of crudity - there is no system to manage includes 
automatically, so the enclosing page must manually list all the 
dependencies necessary for the subcomponents which might arrive. 
Further, no URL rewriting is done upon the template material - which 
means that no URLs (except, presumably, "false" ones!) should appear 
within the template text itself. This in particular means that images 
which are part of the template need to be specified in CSS. I have had a 
cack-handed attempt at doing this for the terrible pencil icon in 
guestbook.html but I hope that Jacobs I, II or III may be able to step 
in here :)

I've tidied up URL handling very slightly in exhibitionView.js, looking 
forward to the days when we have "ViewParameters" but these are still 
some distance off.

As I noted in the previous mail, exhibition/about is currently broken.