Better slides handling

Hello,

I didn't like the idea of needing to hack page.tpl.php for the slides, so I removed it and added an optional region (where you can place a block on that region to place the slides).

Then I wrote a block code (see attachments) that queries for a custom bool field on a page. If it matches, then place the summary as the slide's contents.

You can see the results at https://ansol.org/

Yes, there may be a better solution, I'm not exactly an experience php/drupal hacker, but I hope this patch and block code spark an interesting discussion towards a better solution!

best to ye all,
Rui