[curves] E-521

[Trevor Perrin]

Robert Granger and Michael Scott report a fast E-521 implementation:

http://eprint.iacr.org/2014/852

Based on Haswell numbers, its efficiency seems similar to Goldilocks:

https://docs.google.com/a/trevp.net/spreadsheet/ccc?key=0Aiexaz_YjIpddFJuWlNZaDBvVTRFSjVYZDdjakxoRkE&usp=sharing#gid=0


DJB also timed it on Sandy Bridge, though his numbers are worse than
I'd expect; not sure why:

http://www.ietf.org/mail-archive/web/cfrg/current/msg05349.html


Trevor