[WIP] Compatibility with QuadGK.jl

[MilesCranmer]

cc @mikeingold @stevengj

This is a draft PR to modify one(q) to return one(ustrip(q)) rather than a dimensionless quantity, to match the behavior of Unitful.jl.

Fixes #40

[github-actions]

Benchmark Results

	main	303c25b...	t[main]/t[303c25b...]
Quantity/creation/Quantity(x)	2.9 ± 0.1 ns	2.9 ± 0.1 ns	1
Quantity/creation/Quantity(x, length=y)	3.3 ± 0.1 ns	3.3 ± 0.1 ns	1
Quantity/with_numbers/*real	3.3 ± 0.1 ns	3.3 ± 0.1 ns	1
Quantity/with_numbers/^int	10.1 ± 2.5 ns	10.1 ± 2.5 ns	1
Quantity/with_numbers/^int * real	10.5 ± 2.4 ns	10.5 ± 2.4 ns	1
Quantity/with_quantity/+y	6 ± 0.1 ns	6 ± 0.1 ns	1
Quantity/with_quantity//y	3.7 ± 0.1 ns	3.7 ± 0.1 ns	1
Quantity/with_self/dimension	1.6 ± 0.1 ns	1.6 ± 0.1 ns	1
Quantity/with_self/inv	3.3 ± 0.4 ns	3.3 ± 0.1 ns	1
Quantity/with_self/ustrip	1.6 ± 0.1 ns	1.6 ± 0.1 ns	1
QuantityArray/broadcasting/multi_array_of_quantities	0.198 ± 0.029 ms	0.197 ± 0.017 ms	1
QuantityArray/broadcasting/multi_normal_array	0.0682 ± 0.0015 ms	0.0683 ± 0.0011 ms	0.999
QuantityArray/broadcasting/multi_quantity_array	0.23 ± 0.0042 ms	0.229 ± 0.0034 ms	1
QuantityArray/broadcasting/x^2_array_of_quantities	0.0419 ± 0.0043 ms	0.0409 ± 0.0047 ms	1.02
QuantityArray/broadcasting/x^2_normal_array	8.5 ± 1.1 μs	8.7 ± 1.2 μs	0.977
QuantityArray/broadcasting/x^2_quantity_array	10 ± 1 μs	9.9 ± 1 μs	1.01
QuantityArray/broadcasting/x^4_array_of_quantities	0.116 ± 0.0045 ms	0.117 ± 0.0052 ms	0.989
QuantityArray/broadcasting/x^4_normal_array	0.0584 ± 0.0007 ms	0.0584 ± 0.0008 ms	1
QuantityArray/broadcasting/x^4_quantity_array	0.082 ± 0.0011 ms	0.0819 ± 0.0009 ms	1
time_to_load	0.17 ± 0.0016 s	0.167 ± 0.00028 s	1.02

Benchmark Plots

A plot of the benchmark results have been uploaded as an artifact to the workflow run for this PR.
Go to "Actions"->"Benchmark a pull request"->[the most recent run]->"Artifacts" (at the bottom).