create utility class for the common subset functions needed by attestation.id and attestation-using sites

[SmartLayer]

This class should do the following:

very basic utility Class -> now I call it secp256k1 (I hope not having to change much should Tore and James Brown decided to go to BN curves half way) with the following functions:

• key generation (I'll try to use webcrypto subtle api for browser-side security - warning this thing doesn't work on nodejs)
• creating a point
• point multiplication
• creating a public key from a point
• creating a Pedersen commitment (for hiding)