Mild rejig of the browse pages

This pull request is for a mild rejig of the `/browse/` pages to make them a bit more approachable.

* **Last-edited** information is now in the form "Edited [x] ago by [x] - (version [x] in changeset [x])" rather than a tabulation of the attributes
* Tweaked the ordering in the **heading** eg "Relation: Liverpool Street Station (1571755)" becomes "Liverpool Street Station (Relation 1571755)"
* Tried to make the **tags** section a bit more primary, i.e. the first thing a new visitor might alight upon, rather than confusing things such as changesets or XML
* Didn't remove anything!

There's a bit more blurb, and some screenshots, on [my blog page about it](http://mcld.co.uk/blog/blog.php?407).

I've made a couple of changes to language-strings, which would imply translation needed eventually.

I'm aware there might be deeper changes afoot (sidebar changes etc). I presume my changes are superficial enough that they shouldn't have any impact on larger plans others may have...