HRE idea

[Kavunovskiy 38]

I think it will be cool to add an option like join/leave HRE
As well as the possibility of the country joining to HRE under a peace treaty

@Łukasz Jakowski

[Guguge 35]

I feel like it would make game stupidly easier. Imagine making all of the world join HRE and then as Austria you unite it with reforms and just win.