Tests

Use procedural macro for `g!` and `s!` macros #691

Job	Run time
clippy_check	34s
build	3m 45s
doc-build	25s
test (x86_64-unknown-linux-gnu)	1m 49s
test-alloc (secp256kfun)	1m 27s
Rustfmt	18s
test (armv7-unknown-linux-gnueabihf)	8m 3s
test-alloc (sigma_fun)	25s
test-minimal (secp256kfun)	1m 39s
test-alloc (ecdsa_fun)	1m 28s
test-minimal (sigma_fun)	22s
test-nightly	1m 20s
test-alloc (schnorr_fun)	1m 42s
test-minimal (ecdsa_fun)	1m 12s
test-minimal (schnorr_fun)	1m 15s
	25m 44s

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