Remove Windows Forms references from projects that don't need them.

[ekolis]

** Describe what needs to be improved. **

Even the Common project contains a reference to System.Windows.Forms because it contains save file dialogs of all things. These sorts of references should be moved into a WinForms specific project. And business logic should be moved out of the UI layers when appropriate, into Common or someplace like that.

Perhaps we could also reorganize the different projects into a smaller number; I'm not convinced that we need six of them!

** Describe how this change could impact the quality of the code. **

It would improve separation of concerns and make the code more understandable.