Add alias for rels and relations

[janikapeters]

Functions with both names existed with some taking the same arguments and computing the same thing.

[lgoettgens]

@fingolfin @fieker any objections?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.00%. Comparing base (4b127f8) to head (dc108a0).
⚠️ Report is 41 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2168      +/-   ##
==========================================
+ Coverage   87.93%   88.00%   +0.07%     
==========================================
  Files         127      127              
  Lines       31776    31809      +33     
==========================================
+ Hits        27941    27995      +54     
+ Misses       3835     3814      -21     

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[lgoettgens]

This is unfortunately incompatible with the current Oscar master as this PR here turns https://github.com/oscar-system/Oscar.jl/blob/73e4186aa042c4f719dc06752f82bdd2da1bc572/src/Modules/UngradedModules/SubquoModule.jl#L2175 into a self-call (resulting in a StackOverflow when called).

Since I still want to get this in eventually, I mark this as technically breaking, so we remember to add it to the next breaking AA release.

[fingolfin]

I am fine with this but as you say, there is a problem with doing that in OSCAR. So first we need to change OSCAR to delegate the other way there (resp. turn rels there into an alias for relations).

So someone should open an issue for OSCAR, or provide a PR, to do that.

[fingolfin]

Coming back to this now, I am not so sure I want rels be an alias for relations -- because there is also relators, and for G::FPGroup I'd want rels(G) = relators(G) ...

[fingolfin]

Also note that Hecke defines rels(A::FinGenAbGroup) (and also nrels) but neither relations nor relators.

(That's not an argument for anything, just one more thing to take into account when addressing this)

[lgoettgens]

Coming back to this now, I am not so sure I want rels be an alias for relations -- because there is also relators, and for G::FPGroup I'd want rels(G) = relators(G) ...

We just noticed that there is @alias nrels number_of_relations in Hecke, so @fingolfin agreed that this here would be good to have for consistency.

[lgoettgens]

I am fine with this but as you say, there is a problem with doing that in OSCAR. So first we need to change OSCAR to delegate the other way there (resp. turn rels there into an alias for relations).

So someone should open an issue for OSCAR, or provide a PR, to do that.

This should be easily doable by just removing the line https://github.com/oscar-system/Oscar.jl/blob/73e4186aa042c4f719dc06752f82bdd2da1bc572/src/Modules/UngradedModules/SubquoModule.jl#L2175. But this is only possible once the breaking AA release with this is finished. I thus don't see the necessity to open this trivial PR in Oscar right now.