[RTM when tests pass] Refactor solution with classmethods

[Ipuch]

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• Have you opened/linked the issue related to your pull request? on TOP of [RTR] Solving a critical issue of codeclimate #788 [RTR] Try to refactor a bit the initialisation of Solution #787
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This change is 

[codecov]

Codecov Report

Attention: 69 lines in your changes are missing coverage. Please review.

Files	Coverage Δ
...examples/torque_driven_ocp/example_soft_contact.py	83.58% <100.00%> (ø)
bioptim/gui/plot.py	70.29% <100.00%> (ø)
bioptim/optimization/non_linear_program.py	90.90% <100.00%> (+0.05%)	⬆️
bioptim/optimization/optimal_control_program.py	85.95% <100.00%> (ø)
...ptim/optimization/receding_horizon_optimization.py	95.98% <100.00%> (ø)
bioptim/optimization/solution.py	79.17% <69.60%> (-0.06%)	⬇️

... and 1 file with indirect coverage changes

📢 Thoughts on this report? Let us know!.

[pariterre]

Reviewed 9 of 10 files at r1, 1 of 1 files at r2, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @Ipuch)

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bioptim/optimization/optimal_control_program.py line 2024 at r2 (raw file):

def concatenate_optimization_variables(

To be removed? Or to be put protected?

The merge-base changed after approval.

[Ipuch]

Reviewable status: 9 of 10 files reviewed, 1 unresolved discussion (waiting on @pariterre)

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bioptim/optimization/optimal_control_program.py line 2024 at r2 (raw file):

Previously, pariterre (Pariterre) wrote…

To be removed? Or to be put protected?

Done.

The merge-base changed after approval.

[pariterre]

Reviewed 1 of 1 files at r3, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @Ipuch)