Remove results dict

[1-Bart-1]

• Make solve! less allocating
• Add all the Dict fields to the results struct
• Rewrite plotting functions to use the results struct
• Remove the solve() function

[ufechner7]

I would suggest:

1. remove the first point and put it into a separate issue

To be discussed: Do we want to have one VSMSolution struct, or two, a small and a large one.

[1-Bart-1]

One big struct for now, we can add a smaller one in a new issue. I marked the first point as done, as you did some great progress there already.

[1-Bart-1]

And for the struct field names: we should stay close to the current dict names. But things like "Fx", "Fy", "Fz" can be combined in one "F" or "force" field.

[ufechner7]

@1-Bart-1 Can you please create a pull request, just defining the new version of the VSMSolution struct that you suggest? I would then comment there. I think it would be good to have Union{MVec, Nothing} for new fields like a force. Then we could skip calculating these values when we don't need them, for example using a parameter like shortsolution=true for the solve function.

[ufechner7]

"F" or "force" field

I prefer lower case names for variables and attributes. CamelCase case should be reserved for types and structs.

[1-Bort-1]

One PR, as asked: VSMSolution gets every Dict quantity (cl/cd/cs, lift/drag/side, *_distribution, alpha_uncorrected, rey, q_ref, va_ref_vec, span, AR, areas, center of pressure), filled by solve!; plotting, generate_polar_data, examples, docs and tests move onto it; solve() and calculate_results are removed (BREAKING). Benchmarked solve! before/after.
Built on #389, which rewrites calculate_results and calc_forces!; #391's plot keywords get merged in whichever lands second.
Leaving out a small results struct and renaming the existing cl_dist/cd_dist.