Reorder static to comply with C99 and switch to the inline macro.
Correct function prototypes and avoid unused parameter warnings.
Remove a VERIFY_CHECK for >=0ness on an unsigned type.
Avoid a shadowed variable.
Fix varrious signed/unsigned comparisons.
Avoid unsigned comparison in scalar arith.
Signed/unsigned comparisons in tests.
Avoid forward static decl of undefined functions, also fix a paren warning in the tests.
field_gmp's negate doesn't need to use the magnitude argument.
Enable warnings.

Wno-unused-function is used for the moment because of the checking
 functions which are currently only used by VERIFY but are not (yet?)
 ifdefed out in normal builds.
Merge pull request #102

a099073 Enable warnings. (Gregory Maxwell)
861f9a5 field_gmp's negate doesn't need to use the magnitude argument. (Gregory Maxwell)
f0709ac Avoid forward static decl of undefined functions, also fix a paren warning in the tests. (Gregory Maxwell)
3276e7d Signed/unsigned comparisons in tests. (Gregory Maxwell)
850562e Avoid unsigned comparison in scalar arith. (Gregory Maxwell)
65a14ab Fix varrious signed/unsigned comparisons. (Gregory Maxwell)
e9e0e21 Avoid a shadowed variable. (Gregory Maxwell)
e28a8b8 Remove a VERIFY_CHECK for >=0ness on an unsigned type. (Gregory Maxwell)
2cad067 Correct function prototypes and avoid unused parameter warnings. (Gregory Maxwell)
a4a43d7 Reorder static to comply with C99 and switch to the inline macro. (Gregory Maxwell)
Rewrite mul/sqr for 32bit/64bit

- interleave calculation of the lower and upper partial product ranges, and reduction
- less registers needed, more opportunities for parallel ops
Add equalities relating input and output variables
Add overflow analysis to field_5x52_int128_impl.h
Add overflow analysis to field_10x26_impl.h
Merge pull request #103

f8cce95 Add overflow analysis to field_10x26_impl.h (Pieter Wuille)
a518598 Add overflow analysis to field_5x52_int128_impl.h (Pieter Wuille)
fa0d620 Add equalities relating input and output variables (Pieter Wuille)
5dd421b Rewrite mul/sqr for 32bit/64bit (Peter Dettman)
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.