luck:ed and sign-(octs-)raw go together

• luck:ed generates a public private keypair where the private keypair is generated from SHA512(seed) and the usual EdDSA clamping procedure is done on the first 32 bytes.
• sign-(octs-)raw allows one to sign from a keypair generated with luck (or, from sca(d/s))

scad, scas, scap allows one to 'tweak' a public/private keypair with a scalar

• scad tweaks public and private
• scas tweaks private
• scap tweaks public