clang-tidy fixes, documentation, refactoring.

.clang-tidy

@@ -7,6 +7,7 @@ Checks: >-
   performance-*,
   readability-*,
   -bugprone-lambda-function-name,
+  -bugprone-easily-swappable-parameters,
   -bugprone-reserved-identifier,
   -cppcoreguidelines-avoid-goto,
   -cppcoreguidelines-avoid-magic-numbers,
@@ -21,6 +22,7 @@ Checks: >-
   -modernize-use-nodiscard,
   -modernize-use-trailing-return-type,
   -performance-unnecessary-value-param,
+  -readability-identifier-length,
   -readability-magic-numbers
 
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