build: disable benchmark by default
build: use subdir-objects for automake
build: nuke bashisms
Merge pull request #158

28ade27 build: nuke bashisms (Cory Fields)
Merge pull request #156

8336040 build: disable benchmark by default (Cory Fields)
Merge pull request #157

5190079 build: use subdir-objects for automake (Cory Fields)
Use Co-Z arithmetic for precomputations

- Selected Co-Z formulas from "Scalar Multiplication on Weierstraß Elliptic Curves from Co-Z Arithmetic" (Goundar, Joye, et. al.) added as group methods with new type sep256k1_coz_t.
- Co-Z methods used for A and G point precomputations.
- WINDOW_A size increased to 6 since the precomputation is much faster per-point.
- DBLU cost: 3M+4S, ZADDU cost: 5M+2S.
- Take advantage of z-ratios from Co-Z to speed up table inversion.