autotoc refactoring

Greetings!

I've finished refactoring the AutoTOC content type, as I think I described in 
an earlier post.  Basically what I've done is merge SilvaCustomAutoTOC into 
the Silva AutoTOC content type.  The Silva AutoTOC type will now provide the 
same functionality as my SilvaCustomAutoTOC type.

Since it appears infrae is readying for a bugfix release of 2.0, also 
including this major change in a bugfix release isn't really appropriate.

For the time being, I've placed it in a branch of Silva, here:

https://svn.infrae.com/Silva/branch/Silva2.0-autotoc-refactor

I've made a couple enhancements since the latest CustomAutoTOC release, 
namely:
1) optionally display icons
2) the 'silva' sorting method now works

There's no upgrade script yet, since I don't know the release that infrae will 
include this in, so existing AutoTOC objects may well break.  You'll need to 
delete and recreate them to test this.

Also note that this enhancement does not extend to the 'AutoTOC' element of 
Silva Documents, and it does not break this document element.  However, the 
toc_rendering adapter (which both the AutoTOC type and element use) contains 
all of the feature enhancements.  It will certainly be possible to implement 
controls in kupu and the forms-based editor to provide the same enhanced 
functionality within Silva Documents.

So, please, please, test this out and let me know what you think!  I would 
like to get this into the earliest possible next release of Silva.

Cheers,
Andy