Blocks

I've just committed these two changes, both of which only affect when you're using the block on a module page.

What it now does is that clicking the section heading will just expand/collapse the section, and to bold the link for the current module page.

Once I'd done the first part, it turned out we didn't need the upgraded YUI library! Sorry about that, but I guess at least you're ahead of the game for Moodle 2.0 now.