Implement change_base_ring for hypercomplexes

[HechtiDerLachs]

@micjoswig : This is a prototype for what you asked for during the meeting. Have a look at the tests to see how to get started.

Currently there is little functionality supported for ModuleFPs over the integers. If you show me the type of complexes you're interested in, then I can work on making them available here.

[codecov]

Codecov Report

Attention: Patch coverage is 88.37209% with 10 lines in your changes missing coverage. Please review.

Project coverage is 84.65%. Comparing base (b547c17) to head (97a8671).
Report is 45 commits behind head on master.

Files with missing lines	Patch %	Lines
...imental/DoubleAndHyperComplexes/src/base_change.jl	45.45%	6 Missing ⚠️
...l/DoubleAndHyperComplexes/src/base_change_types.jl	95.00%	2 Missing ⚠️
src/Modules/UngradedModules/FreeModuleHom.jl	60.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master    #3794    +/-   ##
========================================
  Coverage   84.65%   84.65%            
========================================
  Files         600      614    +14     
  Lines       82554    83324   +770     
========================================
+ Hits        69885    70537   +652     
- Misses      12669    12787   +118     

Files with missing lines	Coverage Δ
...perComplexes/src/Morphisms/simplified_complexes.jl	94.61% <100.00%> (+0.01%)	⬆️
...HyperComplexes/src/Objects/new_complex_template.jl	88.46% <100.00%> (+0.96%)	⬆️
src/Modules/UngradedModules/HomologicalAlgebra.jl	92.81% <100.00%> (+0.74%)	⬆️
src/Modules/UngradedModules/Methods.jl	85.71% <100.00%> (+0.07%)	⬆️
src/Modules/UngradedModules/SubQuoHom.jl	77.60% <100.00%> (ø)
...l/DoubleAndHyperComplexes/src/base_change_types.jl	95.00% <95.00%> (ø)
src/Modules/UngradedModules/FreeModuleHom.jl	92.39% <60.00%> (+1.22%)	⬆️
...imental/DoubleAndHyperComplexes/src/base_change.jl	45.45% <45.45%> (ø)

... and 53 files with indirect coverage changes

[micjoswig]

Thanks. I will look it this later, after July 10.

[HechtiDerLachs]

@micjoswig : Any new opinions on this? If yes, we might put this PR on the list for discussion for the upcoming Wednesday meeting.

[micjoswig]

The relevant complexes don't exist in Oscar yet. My basic example would be the boundary complex of a finite simplicial complex.

It is not very difficult. But we need to decide which part we take from polymake (or none at all).

@lkastner @benlorenz

[HechtiDerLachs]

Thanks for the reply.

To my understanding we can proceed with this PR in the meantime. How to bring over applications from Polymake is a different topic, I think. And we will need this functionality for other things, too.

[fieker]

Janko is (organizing or doing a) review

[fingolfin]

@HechtiDerLachs made some updates but tests are failing now. He'll work on it and together with @jankoboehm get this merged.

[fingolfin]

tests are passing now, and here in triage @jankoboehm said he is fine with this being merged, so I'll just do that.