* Update Some Doc Block Annotations
See PR #2010. That PR was never completed, and has gone stale. However, it was correct in identifying a situation where the doc block was not entirely accurate. It did not go far enough - several closely-related methods have similar problems. This PR attempts to fix the original problem and its close relations. Aside from the doc block changes, there are very minor changes to executable code. It also changes some of the unit tests targeted at the methods in question to eliminate mocking in favor of 'real' tests.
* Change Method to Static
Otherwise Scrutinizer will complain, even though Phpstan doesn't.
* Scrutinizer
Various clean-up activities.
* Scrutinizer
@#&$(*#&$ Got complexity down from 53 to (I think) 50. Don't really know what the target is.
* Code Changes Suggested By Review
Some improvements suggested in review by @PowerKiKi.
* Update Cells.php
* Merge Conflict
A change to a parameter name caused several problems when trying to fix it on Github. Fixing it locally should do the trick.
* Merge Conflicts in Phpstan Baseline
PR #2382 made a large number of changes to Phpstan Baseline, some of which conflicted with the Phpstan Baseline changes in this PR. This should resolve them all.
#1495 reports that ActiveSheet can change when calculation
involves jumping around between sheets.
Save index before calculation, restore after, add test.