Improvements to the compiler and to the compilation of CategoryOfColumns

[zickgraf]

The changes in this PR are straight-foward, so I will merge the PR without additional review if and when the CI succeeds.

[codecov]

Codecov Report

Merging #699 (8fead39) into master (36eec44) will increase coverage by 0.09%.
The diff coverage is 58.47%.

❗ Current head 8fead39 differs from pull request most recent head 5774adb. Consider uploading reports for the commit 5774adb to get more accurate results

@@            Coverage Diff             @@
##           master     #699      +/-   ##
==========================================
+ Coverage   64.40%   64.49%   +0.09%     
==========================================
  Files         316      316              
  Lines       45084    44997      -87     
==========================================
- Hits        29038    29023      -15     
+ Misses      16046    15974      -72     

Impacted Files	Coverage Δ
CAP/gap/MethodRecord.gi	81.69% <11.11%> (-0.16%)	⬇️
...gap/CategoryOfColumnsAsOppositeOfCategoryOfRows.gi	57.51% <14.28%> (+14.97%)	⬆️
FreydCategoriesForCAP/gap/CategoryOfRows.gi	44.71% <40.00%> (-0.35%)	⬇️
FreydCategoriesForCAP/gap/CategoryOfColumns.gi	46.15% <63.33%> (+0.32%)	⬆️
...recompiled_categories/MatrixCategoryPrecompiled.gi	73.24% <66.66%> (-0.05%)	⬇️
..._categories/OppositeOfMatrixCategoryPrecompiled.gi	45.97% <66.66%> (+0.21%)	⬆️
CompilerForCAP/gap/PrecompileCategory.gi	94.31% <85.18%> (-0.50%)	⬇️
CAP/PackageInfo.g	100.00% <100.00%> (ø)
CAP/gap/OppositeCategory.gi	92.30% <100.00%> (+0.09%)	⬆️
CompilerForCAP/PackageInfo.g	100.00% <100.00%> (ø)
... and 5 more

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