Named placeholder formatting

Hi Daniel and Martin

I added a way to use named placeholders in the translation strings (e.g. {carModel}), because I think it makes it easier for translators to use than the normal string format {0} parameters.

I am using a method developed by Phil Haack: http://haacked.com/archive/2009/01/04/fun-with-named-formats-string-parsing-and-edge-cases.aspx

Use it if you like :)