Port es25519.cc to nan 1.6.2
Port es25519.cc to nan 1.6.2

Signed-off-by: Kenan Sulayman <9176253dfc0bc82671a5e984646605f93319147a@sly.mn>

dazoe/ed25519,KenanSulayman/ed25519,KenanSulayman/ed25519,KenanSulayman/ed25519,KhaosT/ed25519,dazoe/ed25519,dazoe/ed25519,KhaosT/ed25519,KhaosT/ed25519,dazoe/ed25519,masonforest/ed25519,KhaosT/ed25519,masonforest/ed25519,masonforest/ed25519,KenanSulayman/ed25519,masonforest/ed25519