Feature nav updates

Hello all,

This PR will add proper toggling to the main nav when on mobile, so it starts closed and lets mobile users see at least some of the page content.

I've had to make a bit of a change to the nav's HTML to accomplish this, but it's not much more than the toggle button, an extra wrapping div, and the inclusion of the Bootstrap Collapse javascript.

This PR also adds a lot for IE6, on which the templates should now be in a readable state. I've had to drop the show/hide navigation and just make it one big vertical list. Anything more complex has just not been achievable without totally changing the nav and big chunks of the page layouts (thereby saddling you guys with a ton of work!).

I've also attempted to fix transparent PNGs on IE6 - I've been able to fix IMG tags in the modules, but not background images. This was the best compormise, every other method I tried caused big chunks of each page to vanish. If that's a concern for you guys then unfortunately at this point you'll just have to use JPGs for background images, apologies.

Everything's up now on http://odi-stg.whiteag5.tryingitout.co.uk/home.html

If there are any questions this PR throws up please just give me a shout.

Thanks,

Gareth