feat: Groebner Walk

[welpj]

Implementation of the Gröbner Walk.

This branch contributes the following algorithms:

• Gröbner Walk
• Pertubed Gröbner Walk
• Fractal Walk
• Generic Walk
• Tran´s version of the Groebner Walk

[fingolfin]

Hi there,

thanks for your contribution. (Out of curiosity: who are you? Are you a member of the SFB-TRR 195 or outsider?)

I am afraid this PR will need some major revisions. E.g. just on the surface level: test related files should be in test/GroebnerWalk; runtests is missing a file extension; there are typos in filenames ("Utilitys" -> "Utilities"). But then also inside there are a structural issues.

Perhaps it'd be best to discuss this via a video chat instead of lengthy comments here.

[tthsqe12]

I would also suggest that Singular.jl is not necessarily the place such a large feature as this. Singular.jl is mainly for an interface to singular, and features like this belong in other packages. But, I am open to having my mind changed on this point.

[fingolfin]

I just talked to @ederc on the phone who explained the background of this PR: @welpj is a master student of him and Anne. This PR will be revised. And he also said that perhaps it should rather go into Oscar.jl.

So, we can just leave this PR aside for the moment, until Anne and Christian tell us it is ready (resp. move it to Oscar.jl)