Feature Request: G1, G2, Pairing Operations available externally

[xcshuan]

There are some scenarios that require the operations of Pairing, not just signature verification, but need to operate G1, G2, GT add, mul, pairing and other operations to design specific pairing-based cryptographic schemes.

herumi implements the pairing library with C++（mcl）, and based on this, the bls library （bls) is implemented, so can this library be split into two libraries? A pairing library is used for actual calculations, and the bls library wraps the pairing library to implement the signature scheme.