disallow using chips that use the current chip c as a building block when editing c

[HannesGitH]

do catch recursive loops early on so it wont cause problems later on

in my case i just finished building a 8by8 bit multiplier but then noticed i was currently editing my one-bit adder, so the one bit adder was now a 8by8 multiplier;
as i didnt want to loose my multiplier and couldnt figure out how to undo that i paniced and tried to export it quickly but through the recursive loop that couldnt finish and now i cant open my save anymore and lost it all :/ damn :D

so yeah disallowing recursive placement early on would be useful ;)

[crispeeweevile]

E, I bet that bug has been here a while (though technically one could say it's not a bug)