* add faster cofactor clearing and tests for g1

* add faster cofactor clearing and tests for g2

parameters of endomorphisms are wrong for now

* add h_eff to g2 tests for correctness


test

* improve cofactor tests g2

* add a test for psi(psi(P)) == psi2(P)

* fix bls12-377 psi & psi2 computation parameters

* rename const to DOUBLE_P_POWER_ENDOMORPHISM_COEFF_0 and make private

* fix clippy warnings in changed code

* remove bls12-381-specific in line comment

* update code comments, make methods private

* master should be patched with master

* update changelog