Integrate new solver

[stfnp]

For the past year or so I have been working on a complete rewrite (and redesign) of the VirtualBow solver, i.e. the part that does the numerical computations. Unlike the old solver, the new one is written in Rust instead of C++ (see also #215). Even though the new solver is not yet finished, it has reached a state where it can be integrated into the main application in order to make testing and filling in missing features easier. This is currently happening on the branch integrate-new-solver (not usable yet).

This issue is for tracking the progress and the remaining tasks and will be updated frequently.

Remaining tasks for the integration

• [x] Include Rust compilation in the main build process
• [x] Make CI/CD pipeline work
• [x] Run solver tests in the pipeline
• [x] Call new solver from main application
• [x] Finalize new solver's output format
• [x] Load new solver output from the main application

Remaining tasks/missing functionality of the new solver

• [x] Add back test test_load_output
• [ ] Evaluation and output of layer stresses
• [x] Dynamic simulation, including output of correct arrow position
• [x] Damping of limb and string
• [x] Manually test new string damping to verify that it does something
• [x] New string model without penalty contacts
• [x] Split solver into two crates: virtualbow-lib and virtualbow-cli and add back integration tests for the command line interface.

More detailed solver issues

• [ ] Progress estimation for dynamic simulation
• [ ] Check for/fix duplicate time point in the dynamic output
• [ ] Document test example of nonlinear pendulum
• [ ] Extend static tests to bows with recurves
• [ ] Implement stiffness of the force/draw curve
• [x] Timestep estimation or control for the dynamic simulation
• [x] Add missing documentation for eigenvalue solver
• [ ] Check for self-intersecting geometry (curvature too high for thickness)
• [x] Implement Error trait for all custom errors
• [x] In solvers, check if states are finite and abort early if not
• [x] Better method than trapezoidal rule for segment stiffness matrices?
• [ ] Add tests for cubic spline extrapolation
• [x] Consider replacing soa_derive with https://github.com/tim-harding/soa-rs
• [x] Proper error handling for computation of natural frequencies

Final details/cleanup

• [ ] Document evaluation of stresses and strains for the new beam elements
• [ ] Include source for choice of corotational reference frame https://apps.dtic.mil/sti/tr/pdf/ADA358178.pdf
• [ ] Document that files older than 0.7 are no longer supported
• [ ] Have a look at all the TODO comments in the code
• [ ] Have a look at all the unwrap() and expect() calls in the code
• [ ] Run Clippy and maybe include in the CI build as well
• [ ] Make warnings errors in the CI build

Keep for later

• [ ] Use GXBeam as a reference for the beam verification examples. Also pick beam length != 1.
• [ ] Re-simulate user bows where the results didn't match well

Issues that need to be revisited after integrating the new solver

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