Test week branch

hey @roosmaa , let's start with pull requests.

The issues #310, #315 should be fixed. I have included my own version of "New Project" and "New Client" screens.
Don't use property for this. If it's a property, it should also be databound (emit PropertyChanged event when it changes).

Better make it into a FormatDuration() function (like GetDuration) or even an extension method for TimeSpan's.