Better gate creation sequence for IC assembler

[evg-zhabotinsky]

IMHO just going in spirals is not interesting enough, and it also takes more time than necessary.
Maybe create gates in a more optimized fashion?

For example, choosing adjacent gate to be created next, with some directional preference, works a bit faster and looks better IMHO. (It feels like the assembler understands your design a bit, e.g. it draws whole tracks at once.)
An example (suboptimal) implementation (which I use myself) can be found in my pull request #115 .

Maybe one can come up with a better solution.
Or can just say that nobody cares :-)