Oh, but I don't feel at all as though we are discussing something that would violate the TOU of this forum.
Let me explain...
Start up your iTunes and select the iTunes Store.
Click on your Apple ID on the left and select Account.
Have a look at your Account Information > Apple ID Summary and notice the option Change Country or Region.
That option is there for a good reason.
And another thing, in the meantime I have contacted Apple Support for iTunes and in their first reaction they say that it is possible to change the country under certain conditions.
There are still a couple of things that are not quite clear for me, therefore I cannot say that my problem is solved yet.