* add more Fp tests for Twisted Edwards curves
* add fused sqrt+division bench
* Significant fused sqrt+division improvement for any prime field over algorithm described in "High-Speed High-Security Signature", Bernstein et al, p15 "Fast decompression", https://ed25519.cr.yp.to/ed25519-20110705.pdf
* Activate secp256k1 field benches + spring renaming of field multiplication
* addition chains for inversion and sqrt of Curve25519
* Make isSquare use addition chains
* add double-prec mul/square bench for <256-bit prime fields.