Fix non-adaptive interpolation

[ErikQQY]

Fix: #199

[ChrisRackauckas]

copy that example to a test case?

[github-actions]

Benchmark Results

	master	3f31f89...	master/3f31f8946c4356...
Simple Pendulum/IIP/BoundaryValueDiffEq.MIRK2()	6.28 ± 0.09 ms	6.47 ± 0.22 ms	0.971
Simple Pendulum/IIP/BoundaryValueDiffEq.MIRK3()	2.21 ± 0.027 ms	2.29 ± 0.074 ms	0.966
Simple Pendulum/IIP/BoundaryValueDiffEq.MIRK4()	0.766 ± 0.02 ms	0.78 ± 0.028 ms	0.982
Simple Pendulum/IIP/BoundaryValueDiffEq.MIRK5()	0.805 ± 0.02 ms	0.818 ± 0.029 ms	0.984
Simple Pendulum/IIP/BoundaryValueDiffEq.MIRK6()	0.919 ± 0.021 ms	0.93 ± 0.027 ms	0.988
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = false)	1.34 ± 0.059 ms	1.36 ± 0.14 ms	0.989
Simple Pendulum/IIP/MultipleShooting(10, Tsit5; grid_coarsening = true)	2.61 ± 0.096 ms	2.65 ± 0.25 ms	0.984
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = false)	0.0369 ± 0.0058 s	0.0382 ± 0.0055 s	0.966
Simple Pendulum/IIP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.116 ± 0.0036 s	0.124 ± 0.0041 s	0.935
Simple Pendulum/IIP/Shooting(Tsit5())	0.191 ± 0.0083 ms	0.191 ± 0.0071 ms	1
Simple Pendulum/OOP/BoundaryValueDiffEq.MIRK2()	0.0405 ± 0.00083 s	0.0453 ± 0.0012 s	0.893
Simple Pendulum/OOP/BoundaryValueDiffEq.MIRK3()	11.6 ± 0.14 ms	13.1 ± 0.25 ms	0.885
Simple Pendulum/OOP/BoundaryValueDiffEq.MIRK4()	3.31 ± 0.044 ms	3.67 ± 0.079 ms	0.902
Simple Pendulum/OOP/BoundaryValueDiffEq.MIRK5()	3.36 ± 0.044 ms	3.71 ± 0.093 ms	0.905
Simple Pendulum/OOP/BoundaryValueDiffEq.MIRK6()	3.48 ± 0.042 ms	3.89 ± 0.11 ms	0.894
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = false)	3.35 ± 0.69 ms	3.65 ± 1.1 ms	0.918
Simple Pendulum/OOP/MultipleShooting(10, Tsit5; grid_coarsening = true)	6.01 ± 1.1 ms	6.23 ± 1.4 ms	0.964
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = false)	0.128 ± 0.012 s	0.138 ± 0.011 s	0.927
Simple Pendulum/OOP/MultipleShooting(100, Tsit5; grid_coarsening = true)	0.404 ± 0.0025 s	0.416 ± 0.0016 s	0.971
Simple Pendulum/OOP/Shooting(Tsit5())	0.751 ± 0.12 ms	0.763 ± 0.041 ms	0.985
time_to_load	5.89 ± 0.046 s	5.96 ± 0.14 s	0.988

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).

[ErikQQY]

To avoid introducing plotting stuff in the test suite, I added some interpolations tests for non-adaptive MIRK solving

[ChrisRackauckas]

That's fine