Properly re-indent template files

As discussed on a recent team chat, we should re-indent the template files, so that HTML errors are easier to spot.

As re-indenting anything on trunk makes it really hard to merge stuff into it from branches, we should do this as late in the 2.3 development cycle as possible (so we have as few merges from branches/v2.1 as possible), while still prior to the QA process (so we can catch any - unlikely as they are - indenting issues in the QA).

We should definitely do this before branching for 2.3, though (so branches/v2.3 -> trunk merges are doable).