Add SR2013 comp and kickstart dates to home page

Alistair has just announced the dates.
Remove obsolete and broken link from walkthrough

There was a link to the "query" object that we used to have. This
patch removes it.
Fix markup of link on kit page

"Charging the batteries" was supposed to be a link, but it was not.
Update the walkthrough's battery-related instructions

These were still related to the SLA batteries.
Add some styling for docs API info

Currently APIs are documented using bulletted lists and aren't very
readable. This allows the use of definition lists instead.
Improve the vision docs API formatting

Use definition lists instead of bulletted lists to format the API docs.
Add a template for news articles and show PUB_DATE

We were storing the publication date of news articles but not using it
on the news article page itself. It's now shown in the top right of a
news article page.
Add 'Back to News' links on news article pages

Makes it slightly easier to navigate the site.
Allow for bottom links on both the left and right

Previously the bottom link was not explicitly floated to the left,
therefore it wasn't possible to also have a link on the right at the
same time.

Also moved the top/bottom link style definitions to main.css as they're
now used on multiple pages throughout the site.
Change news page to use standard bottom links

As part of the development of the team-status stuff I created a bunch of
CSS classes for top/bottom tab-style links that are useful for
previous/next or back buttons. This style of link is now used on the
team-status pages and the news article pages. This commit alters the
'older news'/'newer news' links on the news page to match the rest of
the site.
Insert the top/bottom link arrows in CSS

They're not really content and might confuse screen readers. Makes sense
to insert them in the stylesheet as they're a style thing.
Fix bug in news page older/newer link generation

When on a news page that has both newer and older stories the 'newer'
link pointed to the wrong place.
Make news item titles links to the article pages

Each news item has its own article page but it's currently quite hard to
find how to get to it. You either have to click through to it from the
homepage or notice, and understand the grey 'permalink' link underneath
the news item on the news page. This makes the news item title into a
link to the article page so that the website is a bit more intuative to
use.
Add newer/older links to the bottom of news pages
Display full news article in RSS description field

Closes #653.
Fix news page generation

The previous commit broke the generate of the news page and partially
broke the latest news item on the homepage. This ensures that the
generated RSS only contains the full article in the description field
while all internal uses of the RSS feed receive the short description.
Update the kickstart date

The kickstart date has recently been changed from the 13th of October
to the 3rd of November.  This patch updates the date on the home
page.
Fix the language about robot budgets.

A teacher assumed that this langauge implied cost. I think this
clarifies the issue.

Signed-off-by: Sam Phippen <samphippen@googlemail.com>
The competition date is _preliminary_.

We don't want to commit to that date right now, when we don't have any
bookings confirmed.
Add the Python: A whirlwind tour tutorial