[Retros] Add units: 17th update (1RA)

[Mu-Tsun Tsai]

> This last one is very fine.


Thank you! :)


> I agree, and can I suggest replacing WQc5 with WR?


Yes indeed, just another quick saving for the material.
Although I did try to avoid using promoted piece, but based on the economic 
standard we're using here, we should do that.

Diagram:
http://www.janko.at/Retros/d.php?ff=8/PP6/1PR5/1BR5/P7/PkN5/NP1P4/2K5
(14+1)