gcd performance

[blegat]

https://github.com/JuliaSymbolics/SymbolicUtils.jl relies on gcd to simplify fractions.
This is currently the performance bottleneck and while the current implementation was focused on correctness, we should now perform a detailed performance benchmark and eliminate bottlenecks.
Possible improvements are:

• Reduce allocation by making use of MutableArithmetics
• Flip order of terms so that leading monomial can be efficiently dropped in-place
• Specialized implementation of univariate polynomial so that univariate GCD which is the base case of the recursion is as fast as possible (preliminary work in https://github.com/JuliaAlgebra/MultivariatePolynomials.jl/tree/bl/univariate)

It would also be relevant to compare to https://github.com/YingboMa/SIMDPolynomials.jl

Below is the results of #205 after the following PRs:

• Add default term and polynomial representations #199
• Speedup for content #200
• Specialize on function type #208
• Avoid closure for operate! on +/- #209
• Zero-allocation terms/coefficients/monomials for AbstractTermLike #210
• More performance #201

Benchmark 1

SIMDPolynomials v0.1, DynamicPolynomials v0.4.5, TypedPolynomials v0.3.2

	Time	Alloc	Memory
SIMDPolynomials
DynamicPolynomials	6.276 ms	123655	4.90 MiB
TypedPolynomials	4.040 ms	94216	3.21 MiB

After #199

	Time	Alloc	Memory
SIMDPolynomials	3.880 ms	95459	3.22 MiB
DynamicPolynomials	6.026 ms	121182	4.75 MiB
TypedPolynomials	3.751 ms	91794	3.10 MiB

After #200

	Time	Alloc	Memory
SIMDPolynomials	3.052 ms	86958	2.59 MiB
DynamicPolynomials	4.946 ms	107489	3.84 MiB
TypedPolynomials	3.139 ms	86455	2.58 MiB

After #208

	Time	Alloc	Memory
SIMDPolynomials	2.996 ms	86695	2.58 MiB
DynamicPolynomials	4.807 ms	107489	3.84 MiB
TypedPolynomials	3.050 ms	86217	2.58 MiB

After #209

	Time	Alloc	Memory
SIMDPolynomials	3.024 ms	82269	2.48 MiB
DynamicPolynomials	5.273 ms	107489	3.84 MiB
TypedPolynomials	2.973 ms	81791	2.48 MiB

After #210

	Time	Alloc	Memory
SIMDPolynomials	3.346 ms	81929	2.47 MiB
DynamicPolynomials	5.907 ms	107321	3.83 MiB
TypedPolynomials	3.596 ms	81451	2.46 MiB

After #217

	Time	Alloc	Memory
SIMDPolynomials	2.894 ms	82941	2.48 MiB
DynamicPolynomials	5.087 ms	106752	3.77 MiB
TypedPolynomials	2.890 ms	82131	2.47 MiB

After #218

	Time	Alloc	Memory
SIMDPolynomials	2.991 ms	82841	2.47 MiB
DynamicPolynomials	4.929 ms	106733	3.77 MiB
TypedPolynomials	3.028 ms	82123	2.47 MiB

Benchmark 2

SIMDPolynomials v0.1, DynamicPolynomials v0.4.5, TypedPolynomials v0.3.2

	Time	Alloc	Memory
SIMDPolynomials	4.234 μs	94	8.06 KiB
DynamicPolynomials	262.587 μs	4817	291.62 KiB
TypedPolynomials	117.350 μs	2021	91.28 KiB

After #199

	Time	Alloc	Memory
SIMDPolynomials	42.200 μs	1104	48.12 KiB
DynamicPolynomials	258.029 μs	4691	284.20 KiB
TypedPolynomials	80.639 μs	1517	62.34 KiB

After #200

	Time	Alloc	Memory
SIMDPolynomials	21.231 μs	623	25.92 KiB
DynamicPolynomials	151.213 μs	2656	161.92 KiB
TypedPolynomials	47.272 μs	823	35.17 KiB

After #208

	Time	Alloc	Memory
SIMDPolynomials	18.073 μs	582	25.17 KiB
DynamicPolynomials	153.686 μs	2656	161.92 KiB
TypedPolynomials	42.174 μs	785	34.47 KiB

After #209

	Time	Alloc	Memory
SIMDPolynomials	18.729 μs	450	22.64 KiB
DynamicPolynomials	156.125 μs	2656	161.92 KiB
TypedPolynomials	42.091 μs	657	31.97 KiB

After #210

	Time	Alloc	Memory
SIMDPolynomials	19.147 μs	437	21.84 KiB
DynamicPolynomials	178.418 μs	2647	161.22 KiB
TypedPolynomials	46.409 μs	640	30.84 KiB

After #217

	Time	Alloc	Memory
SIMDPolynomials	16.274 μs	423	19.61 KiB
DynamicPolynomials	149.753 μs	2494	152.22 KiB
TypedPolynomials	26.885 μs	345	20.28 KiB

After #218

	Time	Alloc	Memory
SIMDPolynomials	11.822 μs	351	17.55 KiB
DynamicPolynomials	139.923 μs	2433	147.75 KiB
TypedPolynomials	25.341 μs	341	20.03 KiB

Benchmark 3

SIMDPolynomials v0.1, DynamicPolynomials v0.4.5, TypedPolynomials v0.3.2

	Time	Alloc	Memory
SIMDPolynomials	432.164 μs	1159	588.06 KiB
DynamicPolynomials	29.397 ms	511347	30.37 MiB
TypedPolynomials	5.521 ms	116743	5.84 MiB

After #199

	Time	Alloc	Memory
SIMDPolynomials	7.483 ms	195099	8.05 MiB
DynamicPolynomials	29.439 ms	502251	29.67 MiB
TypedPolynomials	3.605 ms	91338	4.38 MiB

After #200

	Time	Alloc	Memory
SIMDPolynomials	2.715 ms	76147	3.05 MiB
DynamicPolynomials	13.290 ms	222506	13.10 MiB
TypedPolynomials	2.509 ms	66448	3.01 MiB

After #208

	Time	Alloc	Memory
SIMDPolynomials	2.668 ms	75839	3.04 MiB
DynamicPolynomials	12.821 ms	222506	13.10 MiB
TypedPolynomials	2.332 ms	66152	3.01 MiB

After #209

	Time	Alloc	Memory
SIMDPolynomials	1.780 ms	34412	2.01 MiB
DynamicPolynomials	13.720 ms	222506	13.10 MiB
TypedPolynomials	1.254 ms	24725	1.97 MiB

After #210

	Time	Alloc	Memory
SIMDPolynomials	1.632 ms	32239	1.89 MiB
DynamicPolynomials	17.388 ms	221419	13.02 MiB
TypedPolynomials	1.389 ms	22552	1.86 MiB

After #217

	Time	Alloc	Memory
SIMDPolynomials	1.678 ms	31108	1.83 MiB
DynamicPolynomials	13.646 ms	209332	12.52 MiB
TypedPolynomials	840.497 μs	5060	1.43 MiB

After #218

	Time	Alloc	Memory
SIMDPolynomials	1.398 ms	30836	1.82 MiB
DynamicPolynomials	13.404 ms	209192	12.51 MiB
TypedPolynomials	820.093 μs	5044	1.43 MiB

cc @shashi