Refactor towards MathematicalSystems.jl

[blegat]

Goes a bit further compared to #388

[johnaoga]

This is clearer!
I think that we also need to set down some rules that we use internally to name and write things and that will help to be consistent writing new code/algorithms. Ping @blegat @adrienbanse @JulienCalbert

[adrienbanse]

@johnaoga I cannot find lowercase for functions and uppercase for structures in JuliaFormatter.

@blegat Is there any other option? Otherwise let's just be strict in the reviews

[johnaoga]

@adrienbanse yeah, that why we need to have some rule between us to complement what's missing in the formatter.

[blegat]

I like to follow the JuMP style guide https://jump.dev/JuMP.jl/stable/developers/style/ 😇