Tests

Use procedural macro for `g!` and `s!` macros #692

Job	Run time
Rustfmt	15s
doc-build	23s
build	3m 47s
test (x86_64-unknown-linux-gnu)	1m 49s
clippy_check	30s
test (armv7-unknown-linux-gnueabihf)	7m 49s
test-alloc (secp256kfun)	1m 54s
test-minimal (secp256kfun)	2m 4s
test-alloc (sigma_fun)	25s
test-nightly	1m 23s
test-minimal (sigma_fun)	29s
test-alloc (ecdsa_fun)	1m 26s
test-minimal (ecdsa_fun)	1m 34s
test-alloc (schnorr_fun)	1m 30s
test-minimal (schnorr_fun)	1m 21s
	26m 39s

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