Remove unused methods in CCOpt

[frapac]

Looking at the current code in CCOpt, I am wondering if we can remove the following files:

• src/Models/fischer_burmeister_relaxation.jl
• src/Models/chen_chen_kanzow_relaxation.jl
• src/Models/lasry_lions_penalty.jl
• src/Models/natural_residual_relaxation.jl

I think it's better if we focus exclusively on interior-point methods in CCOpt (at least for now). An idea would be to move these files in a new package called CCOpt-experiments.jl.

Let me know what is your opinion.

[apozharski]

Yep, I am 100% onboard with moving these to an experiments package, and I think that is the best way to deal with the more experimental ideas.

We can also probably get rid of: src/Solvers/relaxation/project.jl and the current magic step options as this approach did not work.

[frapac]

that works for me.

[apozharski]

Addressed by #68