[Retros] Add units: N2Ci

[Mu-Tsun Tsai]

Hi everyone,

I just came up with a new N2Ci design, it is 7+1, two pieces fewer than 
the current record.

Diagram:
http://www.janko.at/Retros/d.php?ff=4R2k/5PP1/6PR/5P1P/8/8/8/8
Stip: Add 2 units.

Intended solution: +WKf8, +BBh7 (the only possible piece that prevents 
retro-stalemate)

Please let me know if this one is correct. Thanks :)

Mu-Tsun