added key format for self connected combinators

[Fl0GUI]

fix for #118

I have tested this with:

• the blueprint from that issue

• a combinator with both red and green cables connected 0eNqNUc1ugzAMfhefs6l0LWyobzJNKCReZwkcZEI1hPLuc8IOPW29RLL9/eSzN+iHBSchjtBuQC7wDO37BjNd2Q65F9cJoQWKOIIBtmOuPDryKE8ujD2xjUEgGSD2+A1tlT4MIEeKhLtaKdaOl7FHUcBfOgamMCs1cHZXuZeqNrAq61A/n9XFk6Db50cD+uMoYeh6/LI3Ur6SflU7nfmiNOduzhZtDnrItHGyUgxbuEBuTKsSFo7dp4SxI54WhUZZMKViw7tr0aryI+jv05EvyRyJWyiW8pg3cRVE/h+oJsfHVKtHVRWYUgaX47V3tzZwQ5n3Hb5Wp+b01tSNLvhcp/QDdtC01w==

• a generic, bigger blueprint

It is literally the first time I look at this repo so even though those three tests worked, it might still fail somewhere.