Add default term and polynomial representations

[blegat]

Part of #194

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

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

Benchmark 3

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

	Time	Alloc	Memory
SIMDPolynomials	42.141 μs	1104	48.12 KiB
DynamicPolynomials	262.718 μs	4691	284.20 KiB
TypedPolynomials	80.060 μs	1517	62.34 KiB

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