Switch delegation order of sub and getindex for submatrices

[lgoettgens]

as per the discussion in Nemocas/Nemo.jl#2194

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.08%. Comparing base (31ea1cd) to head (68869da).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2252      +/-   ##
==========================================
- Coverage   88.08%   88.08%   -0.01%     
==========================================
  Files         126      126              
  Lines       31728    31729       +1     
==========================================
  Hits        27949    27949              
- Misses       3779     3780       +1     

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[thofma]

Yay. I think we should also make the code in Nemo accept Integer and make everything reduce to the Int case. What do you think @lgoettgens? (Asking you since you unfortunately had to look at this).

[lgoettgens]

Yay. I think we should also make the code in Nemo accept Integer and make everything reduce to the Int case. What do you think @lgoettgens? (Asking you since you unfortunately had to look at this).

I agree, but I don't have the capacity to do this right now