Add an Atreus default layout

[benreyn]

No description provided.

[technomancy]

Thanks for adding this; would love to see it merged.

[benreyn]

I think I still need to tweak it some. I think the Pin layout ended up being wrong on it, but I can update it if @ruiqimao has any interest in getting this merged.

[technomancy]

Sure; unfortunately I can't test it till it's deployed because of #33, (and also due to the fact that it's node which I know nothing about) but if you have any specific questions go ahead and let me know.

[benreyn]

I think I worked all the kinks out, (based on the testing I did with the atreus I built) but again, I dont see much point in picking this back up unless there is interest in getting it merged.

[ironfish]

+100 for merging

[benreyn]

Well, there was enough interest from others that I went ahead and fixed the wiring and pin layout for this to match what someone might have after building an atreus following @technomancy's guide. I amended the commit and force pushed this branch so it should be good to go if @ruiqimao wants to merge it in.

[pcewing]

I am interested in this being added (And potentially Atreus62); I may take a crack at the 62 key version based on this PR