Use automatic mapping between entity objects and DTO / ViewModels

Currently, the code uses handwritten mapping functions (extension methods). It is quite possible that using tools such as AutoMapper or http://www.devtrends.co.uk/blog/stop-using-automapper-in-your-data-access-code could simplify this. We will probably never get rid of all hand-mappings, but it should be possible to reduce the amount of boilerplate code.

Needs more investigation.